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d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.3.3 Incoming SDP offer without ECN | If the IMS-ALG receives a SDP offer without the "a=ecn-capable-rtp" attribute and all of the following conditions apply:
- the IMS-ALG knows via configuration that the IMS-AGW supports acting as ECN endpoint; and
- the IMS-ALG knows via configuration that the succeeding network supports ECN,
then the IMS-ALG may include the "a=ecn-capable-rtp" attribute in the offer it forwards towards the succeeding node, indicating the related capabilities of the IMS-AGW.
If the IMS-ALG inserted ECN attributes in the SDP offer and receives an SDP answer containing the "a=ecn-capable-rtp" attribute, the IMS-ALG shall return the SDP answer to the preceding node removing the "a=ecn-capable-rtp" attribute, and will configure the IMS-AGW to act as an ECN endpoint. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.4 IMS-ALG in P-CSCF for Optimal Media Routeing (OMR) | Based on operator policy, the P-CSCF shall remove OMR related SDP attributes before it sends an SDP offer or answer towards an UE, as specified in subclause 2.1.9 of 3GPP TS 29.079 [11D]. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.5 IMS-ALG in P-CSCF for NA(P)T and NA(P)T-PT controlled by the P-CSCF | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.5.1 General | This subclause describes the P-CSCF procedures for supporting the scenario where IP address and/or port conversions occur at the IMS-AGW level in the media path between the UE and the backbone. Two types of address conversions are covered:
- IP version interworking (NA(P)T-PT); and
- IP address/port translation (NA(P)T).
When the P-CSCF performs procedures for P-CSCF controlled NA(P)T and NA(P)T-PT, it shall modify the IP address(es) and port numbers (in case of NA(P)T) in SDP offers and answers, based on the IP address(es) and port number(s) received from the IMS-AGW, as described in subclause 6.7.2.1.
For terminating sessions the P-CSCF may towards a UE performing the functions of an external attached network indicate in the SDP offer alternate IP address versions (IPv4 and IPv6) by inserting two "altc" attributes as defined in RFC 6947 [228]. The order of setting the two IP addresses in the two "altc" SDP attributes shall be based on local policy. The insertion of the "altc" attributes is independent of their presence in the received SDP offer.
NOTE 1: The insertion of alternate IP versions allows avoiding the rejection of the SDP offer because of incompatible network address formats and when the request terminates in a corporate network enables the corporate network to avoid IP version interworking.
NOTE 2: The handling of alternative IP addresses between the IMS-ALG and the TrGW is defined in 3GPP TS 23.334. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.6 IMS-ALG in P-CSCF for support of hosted NAT | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.6.1 General | When the P-CSCF performs procedures for hosted NAT, it shall modify the IP address(es) and port numbers, based on the IP address(es) and number(s) received from the IMS-AGW, as described in subclause 6.7.2.1. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.6.2 Hosted NAT traversal for TCP based streams | When the P-CSCF acts as an IMS-ALG, it acts as a B2BUA and modifies the SDP as described as described in 3GPP TS 23.334 [7F]. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.7 IMS-ALG in P-CSCF for support of ICE | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.7.1 General | This subclause describes procedures of a P-CSCF to support ICE, as defined in RFC 8445 [289] and RFC 8839 [290].
NOTE 1: If no IMS-AGW is inserted on the media plane, a P-CSCF might transparently pass ICE related SDP attibutes, in order to support ICE between the UE and remote entities. The remaining procedures in this subclause apply to when the P-CSCF inserts an IMS-ALG on the media plane.
When the P-CSCF with attached IMS-AGW receives SDP candidate information from the offerer, it shall not forward the candidate information towards the answerer. When the P-CSCF receives SDP candidate information from the answerer, it shall not forward the candidate information towards the offerer. The remaining procedures in subclause 6.7.2.7.1 are optional.
NOTE 2: An P-CSCF that removes and/or does not provide ICE related SDP attributes (e.g. a=candidate) in the offer/answer exchange will cause the ICE procedures to be aborted and the address and port information in the m and c lines of the SDP offer will be used. If this address and port information contains the relayed candidate address of a STUN Relay server, as recommended by ICE, then an extra media relay server will be used for the session which is not necessary nor desirable.
The P-CSCF with attached IMS-ALG performs separate ICE procedures towards the offerer and the answerer. The usage of ICE is negotiated separately with the offerer and answerer, and ICE may be applied independently at either side. Furthermore, the P-CSCF may be configured to apply ICE procedures only towards one network side, e.g. towards the IM CN subsystem it belongs to.
NOTE 3: Since the P-CSCF is inserting an IMS-ALG, it can choose to provide the NAT traversal mechanism defined in Annex F towards the UE. In such case the P-CSCF will not provide ICE support towards the UE, but the P-CSCF can still provide ICE support towards the core network in scenarios where ICE is used in the core network, e.g. to support NAT traversal for other access networks with no deploied IMS-ALGs.
Since the P-CSCF is not located behind a NAT, it does not request the IMS-ALG to generate keep-alive messages even when acting as a full ICE entity. The P-CSCF only requests the IMS-ALG to terminate and generate STUN messages used for the candidate selection procedures.
Since the P-CSCF is not located behind a NAT the P-CSCF shall only include host candidates in SDP offers and answers generated by the P-CSCF. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.7.2 P-CSCF full ICE procedures for UDP based streams | 6.7.2.7.2.1 General
This subclause describes the P-CSCF full ICE procedures for UDP based streams.
6.7.2.7.2.2 P-CSCF receiving SDP offer
When the P-CSCF receives an SDP offer including ICE candidate information, the P-CSCF shall send the candidate information for each UDP based stream received in the SDP offer towards the IMS-ALG. If the SDP offer includes TCP candidate information for a UDP based stream, the P-CSCF may send such candidate information to the IMS-AGW, in addition to the UDP candidate information as defined in RFC 6544 [131]. The P-CSCF shall request the IMS-ALG to reserve media- and STUN resources towards the offerer, based on the candidate information, in order to allow the IMS-ALG to perform the necessary connectivity checks per the ICE procedures.
If the offerer is acting as an ICE controller entity the P-CSCF shall act as an ICE controlled entity in the direction towards the offerer. If the offerer is acting as an ICE controlled entity the P-CSCF shall act as an ICE controller entity in the direction towards the offerer.
6.7.2.7.2.3 P-CSCF sending SDP offer
Prior to sending an SDP offer, the P-CSCF may choose to apply related ICE procedues, e.g. if it expects to interact with terminals applying procedures as described in subclause K.5.2, and if both the P-CSCF and IMS-ALG also support ICE procedures. To invoking these ICE procedures, the P-CSCF shall request the IMS-ALG to reserve media- and STUN resources towards the answerer for each UDP based media stream and include a host candidate attribute for each UDP based stream in the SDP offer, providing the reserved address and port at the IMS-ALG as destination. The P-CSCF may also include host TCP candidate information for UDP based streams in the SDP offer as defined in RFC 6544 [131].
The P-CSCF shall always act as an ICE controller entity towards the answerer.
NOTE: The host candidate address included by the P-CSCF in the generated SDP offer matches the c- and m line information for the associcated UDP stream in the SDP offer.
6.7.2.7.2.4 P-CSCF receiving SDP answer
When the P-CSCF receives an SDP answer including ICE candidate information, the P-CSCF shall send the candidate information for each UDP based stream received in the SDP answer towards the IMS-ALG.
The P-CSCF shall request the IMS-ALG to perform ICE candidate selection procedures towards the answerer. The P-CSCF shall request the IMS-ALG to inform the P-CSCF, for each UDP stream, which candidate pair has been selected towards the answerer, once the candidate selection procedure towards the answerer has finished.
If the IMS-ALG indicates to the P-CSCF that, for at least one UDP stream, the selected candidate pair does not match the c- and m- line address information for the associated UDP stream, exchanged between the P-CSCF and the answerer, and the P-CSCF acts an ICE controller entity towards the answerer, the P-CSCF shall send a new offer towards the answerer in order to allign the c- and m- lines address information with the chosen candidate pair for the associated UDP stream.
6.7.2.7.2.5 P-CSCF sending SDP answer
When the P-CSCF generates an SDP answer for an offer that included ICE candidate information, the P-CSCF shall request the IMS-ALG to reserve media- and STUN resources towards the offerer for each UDP based media stream and include an SDP host candidate attribute for each UDP based stream in the SDP answer, providing the reserved address and port at the IMS-ALG as destination.
The P-CSCF shall in the generated SDP answer include host candidate information which matches the c- and m line information for the associated UDP stream in the SDP answer.
The P-CSCF shall request the IMS-ALG to perform ICE candidate selection procedures towards the offerer. The P-CSCF shall request the IMS-ALG to inform the P-CSCF, for each UDP stream, which candidate pair has been selected towards the offerer, once the candidate selection procedure towards the answerer has finished.
If the IMS-ALG indicates to the P-CSCF that the selected candidate pair towards the offerer does not match the c- and m- line address information for the associated UDP stream, exchanged between the P-CSCF and the offerer, and the P-CSCF acts an ICE controller entity towards the offerer, the P-CSCF shall send an offer towards the offerer (which will now act as an answerer) in order to allign the c- and m- line address information with the chosen candidate pair for the associated UDP stream. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.7.3 P-CSCF ICE lite procedures for UDP based streams | When the P-CSCF is using ICE lite procedures for UDP based streams, the P-CSCF procedures are identical as described in subclause 6.7.2.7.2, with the following exceptions:
- The P-CSCF always acts as an ICE controlled entity towards the offerer and towards the answerer; and
- The P-CSCF requests the IMS-ALG to perform ICE lite candidate selection procedures, as defined in RFC 8445 [289]. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.7.4 ICE procedures for TCP based streams | 6.7.2.7.4.1 General
The P-CSCF shall disable ICE procedures for TCP based streams, i.e. streams where TCP is indicated as transport protocol in the m-line. Instead the P-CSCF will use the mechanism defined in RFC 4145 [83] for establishing TCP based streams, as defined in RFC 6544 [131].
NOTE 1: Handling of TCP candidates for UDP based streams is described in subclause 6.7.2.7.2.
NOTE 2: An entity that supports ICE continues the ICE procedures for UDP based streams, even if no candidates are provided for TCP based streams.
6.7.2.7.4.2 P-CSCF receiving SDP offer
When the P-CSCF receives an SDP offer, the P-CSCF shall ignore the candidate attributes for TCP based streams. The P-CSCF shall not send the candidate information for TCP based streams towards the IMS-ALG.
6.7.2.7.4.3 P-CSCF sending SDP offer
When the P-CSCF generates an SDP offer the P-CSCF shall include an "actpass" setup attribute, as defined in RFC 4145 [83], for each TCP based stream, which will cause the answerer to initiate the TCP connections towards the IMS-ALG. The P-CSCF shall not include any candidate attributes for TCP based streams in the SDP offer.
6.7.2.7.4.4 P-CSCF receiving SDP answer
Since the P-CSCF does not include candidates in the SDP offer towards the answerer, there are no ICE specific procedures when the P-CSCF receives an SDP answer.
NOTE: If the SDP answer contains candidate attributes for TCP based streams, the P-CSCF simply discards the candidate attributes.
6.7.2.7.4.5 P-CSCF sending SDP answer
When the P-CSCF generates an SDP answer the P-CSCF shall include a "passive" setup attribute, as defined in RFC 4145 [83], for each TCP based stream, which will cause the offerer to initiate the TCP connections towards the IMS-ALG. The P-CSCF shall not include any candidate attributes for TCP based streams in the SDP answer. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.2.8 IMS-ALG in P-CSCF for transcoding | An IMS-ALG may support procedures to modify SDP for transcoding purposes. The IMS-ALG shall only apply those transcoding procedures if an attached IMS-AGW supports transcoding.
Upon receipt of an SDP offer, based on local policy and SDP signalling inspection, the IMS-ALG may decide to offer transcoding.
To offer transcoding at the IMS-AGW, the IMS-ALG shall add codecs selected by local policy and supported by the IMS-AGW to the SDP offer. The local policy shall be in accordance with the requirements of clause T.2.
Upon receipt of the corresponding SDP answer, the IMS-ALG shall inspect the list of the codecs within the SDP answer and proceed as follows:
- If the list contains at least one of the codecs that was already contained in the previously received SDP offer, no transcoding at the IMS-AGW is required and the IMS-ALG will configure the IMS-AGW accordingly. The IMS-ALG shall remove from the SDP the codecs added to the original offer before forwarding the response to the offerer.
- If only the codecs inserted by the IMS-ALG are contained in the answer, the IMS-ALG will configure the IMS-AGW to transcode. The IMS-ALG shall replace the received codecs in the SDP anwer with the codec it configured the IMS-AGW to use towards the SDP offerer´s direction.
For an IMS-ALG acting as ATCF, the following applies in addition:
- During an originating or terminating session establishment, for media using PS transport towards the UE, the IMS-ALG (ATCF) should pass SDP offers without adding codecs to the SDP offer and pass SDP answers without modification to the contained codecs to avoid the potential need for transcoding in the IMS-AGW before the PS to CS access transfer; and
- during the PS to CS access transfer procedure, the IMS-ALG (ATCF) shall preferentially select from the SDP offer it receives from the MSC server the codec already configured on the corresponding remote leg, if available. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.3 IMS-ALG in ISC gateway function | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.3.1 General | When the ISC gateway function acts as an IMS-ALG, it makes procedures as for an originating UA and terminating UA. The IMS-ALG acts as a B2BUA. For the use of the IMS-ALG for specific capabilities, additional procedures are defined in subsequent subclauses.
NOTE: The internal function of the IBCF as an IMS-ALG is defined in 3GPP TS 29.162 [11A], and the capabilities are identical for the ISC gateway function. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 6.7.3.2 IMS-ALG in application gateway function for support of ICE | The application gateway function shall act according to the procedures defined for the IBCF in subclause 6.7.1.2. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7 Extensions within the present document | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.1 SIP methods defined within the present document | There are no SIP methods defined within the present document over and above those defined in the referenced IETF specifications. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2 SIP header fields defined within the present document | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.0 General | This subclause defines additional header fields. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.1 Void | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.2 Void | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.3 Void | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.4 Void | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.5 Void | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.6 Void | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.7 Void | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.8 Void | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.9 Void | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.10 Void | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.11 Definition of Restoration-Info header field | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.11.1 Introduction | IANA registry: Header Fields registry for the Session Initiation Protocol (SIP)
Header field name: Restoration-Info
Usage: The Restoration-Info header field is used only for informative purposes.
Header field specification reference: 3GPP TS 24.229, http://www.3gpp.org/ftp/Specs/archive/24_series/24.229/
In case of a node failure there are cases where an upstream node can use information about a node failure. The upstream node can use this information for error reporting, or possibly for error recovery.
An upstream node can inform a downstream node about supported error recovery mechanisms. The downstream node can use this information for error recovery. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.11.2 Applicability statement for the Restoration-Info header field | The Restoration-Info header field is applicable within a single private administrative domain or between different administrative domains.
The Restoration-Info header field is applicable when:
1) a node has failed and the SIP node detecting this failure needs to inform a proxy in the administrative domain of the terminating user about the failure; or
2) a proxy located in the private administrative domain of a user wants to send information about the subscriber to a downstream proxy for error recovery.
For case 1) the SIP node detecting the failure can include the Restoration-Info header field set to the value "noresponse" in a 408 (Request Timeout) response to an INVITE request or a 504 (Server Time-out) response to a dialog forming request or standalone transaction,
For case 2) the Restoration-Info header field is included in an initial INVITE request with an "IMSI" header field parameter set to a value identifying the user. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.11.3 Usage of the Restoration-Info header field | A SIP entity that does not receive a response from the next SIP node, may include a Restoration-Info header field in the error response to inform upstream nodes or networks about the downstream node failure. The upstream nodes or networks may use this information to either inform the originating user, to report the failure or to initiate restoration.
A SIP entity in the home network domain may use the Restoration-Info header field to transport an IMSI value to downstream SIP entities. The downstream SIP entity can use this information to initiate restoration for this user. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.11.4 Procedures at the UA | There are no specific procedures specified for a UA. A UAC in a B2BUA may use the information in the Restoration-Info header field for error reporting, or take this information into account when deciding on re-attempting the request. A UAS may include a Retoration-Info header field in an error respons to inform upstream nodes or networks about the downstream node failure. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.11.5 Procedures at the proxy | A SIP proxy that supports this extension and receives a request may insert a Restoration-Info header field prior to forwarding the request. The header field is populated with the IMSI value received in the body of a DIAMETER request as per 3GPP TS 29.228 [14] within the quoted string .
A SIP proxy that supports this extension and receives a request with the Restoration-Info header field, may retrieve the IMSI value from the header field and use it to poulate a DIAMETER request as per 3GPP TS 29.214 [13D] for the purposes of performing PCRF restoration procedures.
A SIP proxy that supports this extension and receives a 408 response with this header field present can use this information for restoration procedures or reporting. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.11.6 Security considerations | The Restoration-Info header field can contain sensitive information. When the Restoration-Info header field contains the IMSI value, it shall be sent only to trusted entities.
A UE is not expected to receive this information. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.11.7 Syntax | The syntax for Restoration-Info header field is specified in table 7.2.11-1.
Table 7.2.11-1: Syntax of Restoration-Info
Restoration-Info = "Restoration-Info" HCOLON pcrf-token / reason / generic-param
pcrf-token = ("IMSI" / ext-type) EQUAL pcrf-param
pcrf-param = quoted-string
reason = "noresponse"
ext-type = token |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.11.8 Examples of usage | The Restoration-Info header field can be inserted by the neighbouring upstream SIP node to the SIP node that does not respond. The header field value "noresponse" can be used to inform the upstream SIP entity about the failure. The upstream SIP entity such as a 3GPP S-CSCF can use this information to initiate restoration procedures. The restoration can be in the form of a lower layer message to the terminating UE to indicate that the UE needs to perform a new SIP registration.
The Restoration-Info header field can be used to transport the IMSI value from the S-CSCF to a P-CSCF. The S-CSCF obtains the IMSI value as a string over the 3GPP Cx interface specified in 3GPP TS 29.228 [14]. The downstream node can include the IMSI string received in a diameter request specified in 3GPP TS 29.214 [13D]. The receiver of this diameter request uses the information to find the UE and indicate that the UE needs to perform a new SIP registration.
The indication to the UE that it needs to perform a new SIP registration is sent over a lower layer. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.12 Relayed-Charge header field | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.12.1 Introduction | IANA registry: Header Fields registry for the Session Initiation Protocol (SIP)
Header field name: Relayed-Charge
Usage: The Relayed-Charge header field is used only for informative purposes.
Header field specification reference: 3GPP TS 24.229, http://www.3gpp.org/ftp/Specs/archive/24_series/24.229/
The P-Charging-Vector header field is used to carry information relating to charging as it accumulates to various entities within the IM CN subsystem. The information within that header field is applicable to the current dialog or transaction at the point where it is received. Sometimes it is appropriate to carry this accumulated charging information, relating to the same dialog or transaction to other entities within the IM CN subsystem. The Relayed-Charge header field is defined to relay the current contents of the P-Charging-Vector header field as known by one entity to another entity with an indication of the Source entity. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.12.2 Applicability statement for the Relayed-Charge header field | The Relayed-Charge header field is applicable within a single private administrative domain or between different administrative domains where there is a trust relationship between the domains.
The Relayed-Charge header field is not included in a SIP message sent to another network if there is no trust relationship.
The Relayed-Charge header field is applicable whenever the P-Charging-Vector header field would be applicable, as defined by RFC 7315 [52]. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.12.3 Usage of the Relayed-Charge header field | A SIP entity that receives a P-Charging-Vector header field may take appropriate fields from the received header field and encode them in the equivalent field within the Relayed-Charge header field, along with a value in the relay-source to indicate the relaying SIP entity.
A SIP UA or SIP proxy that receives a SIP request or response that contains a Relayed-Charge header field can use the values, to produce charging records.
A SIP proxy may remove the Relayed-Charge header field if it is known there is no intended collector of the Relayed-Charge header field subsequent in the path of the request or response. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.12.4 Procedures at the UA | This document does not specify any procedure at a UA located outside the administrative domain of a private network (e.g., PSTN gateway or conference mixer), with regard to the Relayed-Charge header field. UAs need not understand this header field.
However, it might be possible that a UA be located within the administrative domain of a private network (e.g., a PSTN gateway, or conference mixer), and it may interact with the charging entities.
In this case, a UA may insert the Relayed-Charge header field in a SIP request or response when the next hop for the message is a proxy or UA located in the same administrative domain. Similarly, such a UA may use the contents of the Relayed-Charge header field in communicating with the charging entities. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.12.5 Procedures at the proxy | A SIP proxy that supports this extension and receives a request or response without the Relayed-Charge header field MAY insert a Relayed-Charge header field prior to forwarding the message. The header is populated with one or more parameters, as described in the syntax, including but not limited to, a globally unique charging identifier.
If a proxy that supports this extension receives a request or response with the Relayed-Charge header field, it may retrieve the information from the header value to use with application-specific logic, i.e., charging. If the next hop for the message is within the trusted domain, then the proxy should include the Relayed-Charge header field in the outbound message. If the next hop for the message is outside the trusted domain, then the proxy may remove the Relayed-Charge header field.
Per local application-specific logic, the proxy may modify the contents of the Relayed-Charge header field prior to sending the message. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.12.6 Security considerations | It is expected as normal behavior that proxies within a closed network will modify the values of the Relayed-Charge header field and insert it into a SIP request or response. However, these proxies that share this information shall have a trust relationship.
If an untrusted entity were inserted between trusted entities, it could potentially interfere with the charging correlation mechanism. Therefore, an integrity-protection mechanism such as IPsec or other available mechanisms shall be applied in order to prevent such attacks. Since each trusted proxy may need to view or modify the values in the Relayed-Charge header field, the protection should be applied on a hop-by-hop basis. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.12.7 Syntax | The syntax for Relayed-Charge header field is specified in table 7.2.12.1
Table 7.2.12.1: Syntax of Relayed-Charge
relayed-charge = "Relayed-Charge" HCOLON relayed-charge-list
relayed-charge-list = relayed-charge-item *(COMMA relayed-charge-item)
relayed-charge-item = relay-source HCOLON charge-params *(SEMI charge-params)
relay-source = "PCSCF" / "SCSCF" / "IBCF" / "transitfunction" / "ICSCF" / other-source
other-source = token
charge-params are as defined for the P-Charging-Vector header field |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.12.8 Examples of usage | The Relayed-Charge header field is used in situations where there is a need to carry charging information applicable to a dialog or transaction which is not directly pertinent to the next hop. So for example, at the S-CSCF the accumulation of the "transit-ioi" header field parameter for an incoming call is removed and a new accumulation of "transit-ioi" header field parameters started. The received transit-ioi header field parameter accumulation can be passed to the online charging server (acting as an AS in the IM CN subsystem) using the Relayed-Charge header field. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13 Resource-Share header field | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.1 Introduction | IANA registry: Header Fields registry for the Session Initiation Protocol (SIP)
Header field name: Resource-Share
Usage: The Resource-Share header field is used only for informative purposes.
Header field specification reference: 3GPP TS 24.229, http://www.3gpp.org/ftp/Specs/archive/24_series/24.229/
The P-CSCF in the 3GPP architecture is responsible for reserving resources in the media plane. The resources reservation procedure includes the possibility to allow resources to be shared between sessions involving the same UE. The possibility to share resources can be dependent on services controlled by application servers.
Since the P-CSCF is service unaware the P-CSCF can benefit from receiving information from application servers regarding potential resource sharing options. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.2 Applicability statement for the Resource-Share header field | The Resource-Share header field is applicable within a single private administrative domain or between different administrative domains. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.3 Usage of the Resource-Share header field | The P-CSCF can include the Resource-Share header field in the REGISTER request to indicate the support of receiving resource sharing information from application servers in the user's home network or in an subsequent request or response within an existing dialog created by an INVITE request to indicate that resource sharing no longer is possible.
An application server in a user's home network acting as a SIP proxy or a UA may use a Resource-Share header field to transport resource sharing information in any request or response destined for the served user.
The P-CSCF receiving a request or response destined for a served UE containing a Resource-Share header field can use the resource sharing information when reserving resources in the media plane. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.4 Procedures at the UA | An application server acting as a UA that supports this extension and receives a request or response destined for the served user containing an SDP offer or answer may insert a Resource-Share header field prior to forwarding the request or response. The value of the header field set to "media-sharing" or "no-media-sharing". When set to "media-sharing" the header field shall further be populated with the "rules" and "timestamp" header field parameters. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.5 Procedures at the proxy | When a P-CSCF supporting this extension receives a REGISTER request from a served UE, the P-CSCF may insert a Resource-Share header field prior to forwarding the REGISTER request. The value of the header field is then set to "supported".
When the P-CSCF receives an SDP offer or answer from the served UE in a subsequent request or response within an existing dialog and if the SDP offer or answer contains information conflicting with the applied resource sharing, the P-CSCF may include the Resource-Share header field set to "no-media-sharing" in the request or response sent towards the application server.
When an application server acting as a SIP proxy supporting this extension receives a request or response destined for the served user containing an SDP offer or answer, the SIP proxy may insert a Resource-Share header field prior to forwarding the request or response. The value of the header field set to "media-sharing" or "no-media-sharing". When set to "media-sharing" the header field shall further be populated with the "rules" and "timestamp" header field parameters.
When the P-CSCF supporting this extension receives a request or response destined for the served UE containing the Resource-Share header field with the value "media-sharing", the P-CSCF may extract resource sharing rules from the "rules" header field parameter and use the extracted resource sharing rules to populate a DIAMETER request as per 3GPP TS 29.214 [13D] for the purposes of performing resource sharing procedures. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.6 Security considerations | The Resource-Share header field does not contain any information that can disclose user information or the topology of nodes within an operator network. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.7 Syntax | The syntax for Resource-Share header field is specified in table 7.2.13.1
Table 7.2.13.1: Syntax of Resource-Share
resource-share = "Resource-Share" HCOLON r-s-param
r-s-param = r-s-supported / r-s-no-media-sharing / r-s-media-sharing / r-s-other
r-s-supported = "supported" [SEMI origin] *(SEMI generic-param)
r-s-no-media-sharing = "no-media-sharing" SEMI origin *(SEMI generic-param)
r-s-media-sharing = "media-sharing" SEMI origin SEMI resource-sharing-rules SEMI
timestamp *(SEMI generic-param)
r-s-other = other-status *(SEMI generic-param)
other-status = token
origin = "session-initiator" / "session-receiver" / other-origin
other-origin = token
resource-sharing-rules = "rules" EQUAL DQUOTE resource-sharing-rule *(COMMA
resource-sharing-rule) DQUOTE
resource-sharing-rule = [ active-resource-sharing-rule ]
active-resource-sharing-rule = new-sharing-key COLON [ existing-sharing-key-list ]
COLON directionality *( COLON generic-rule-param-value )
new-sharing-key = sharing-key
existing-sharing-key-list = sharing-key *(SLASH sharing-key)
directionality = "UL" / "DL" / "UL-DL" / other-directionality
other-directionality = token
sharing-key = token
generic-rule-param-value = token
timestamp = "timestamp" EQUAL 1*DIGIT |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.8 Operation | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.8.1 General | The values in the "resource-share" header field field are defined as follows:
"supported" indicates that the sender would like to receive information about resource sharing options for sessions involving the UE identified by the "+sip.instance" header field parameter in the Contact header field.
"media-sharing" indicates that an application server has determined that one or more media streams in the session can be subject for resource sharing.
"no-media-sharing" indicates that an application server or the P-CSCF has determined that none of the media streams in the session are subjects for resource sharing.
The Resource-Share header field contains the "origin", "rules" and "timestamp" header field parameters. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.8.2 The "origin" header field parameter | The "origin" header field parameter is used to identify the source of the resource sharing information. The values in the "origin" header field field are defined as follows:
"session-initiator" indicates that the application server or the P-CSCF that included the Resource-Share header field is serving the UE sending the initial INVITE request.
"session-receiver" indicates that the application server or the P-CSCF that included the Resource-Share header field is serving the UE receiving the initial INVITE request. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.8.3 The "rules" header field parameter | The "rules" header field parameter carries one or more rules for resource sharing. Each rule is included in the same order as the corresponding m-line in the SDP offer/answer and consists of the following parts:
"new-sharing-key" this part is mandatory and identifies a media stream in an exisiting ongoing session or is a new sharing key value when the UE is not already involved in a session subject for resource sharing. The same value of the "new-sharing-key" can only appear in one media stream.
"existing-sharing-key-list" this part is optional and is only included in the INVITE request when the request is forked and if there are UEs (registered via a P-CSCF indicating that receiving resource sharing option information would be useful) already involved in sessions where the media-stream can be shared. Each value in the "existing-sharing-list" identifies a media stream in the ongoing session. In the forking case the "new-sharing-key" includes a new sharing key value to be used by UEs not involved in a session yet. The same value of a sharing key in the "existing-sharing-key-list" can only appear in one media stream.
"directionality" this part indicates in which direction resource sharing applies. "UL" indicates that resource sharing can be applied in the direction from the UE. "DL" indicates that resource sharing can be applied in the direction towards the UE. "UL-DL" indicates that resource sharing can be applied in both directions. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.8.4 The "timestamp" header field parameter | The "timestamp" header field parameter indicates when the application server determined the resource sharing rules and is used to determine the most applicable resource sharing option.
NOTE: Since the media streams in several sessions can be shared race conditions can occur due to retransimissions of requests or responses carrying the Resource header field.
The value is a counter unique for each user and is increased and inserted in the header field each time the application server includes a Resource-Share header field in a request or response involving a UE registered by the user.
When the P-CSCF receives a Resorce-Share header field, the P-CSCF extracts and stores the extracted resource sharing rule along with the value of the received "timestamp" header field as follows:
1) if a resource sharing rule identified by the sharing key is not already stored, store the extracted resource sharing rule along with the value of the received "timestamp" header field;
2) if a resource sharing rule identified by the sharing key is already stored with a lower timestamp value than the value of the received "timestamp" header field, replace the stored resource sharing rule with the extracted resource sharing rule along with the value of the received "timestamp" header field; or
3) if a resource sharing rule identified by the sharing key is stored with a higher timestamp value than the value of the received "timestamp" header field, discard the extracted resource sharing rule.
The "timestamp" header field can be reset to "0" when none of the UEs registered by the user is involved in a session any longer. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.9 Examples of usage | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.9.1 Example overview | The following subclauses describe examples on how:
- the P-CSCF indicates in the REGISTER request that P-CSCF supports receiving information about resource sharing;
- the application server sends information about potential resource sharing to the P-CSCF; and
- the P-CSCF extracts resource sharing information for media-streams. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.9.2 The P-CSCF indicates in the REGISTER request that P-CSCF supports receiving information about resource sharing | When P-CSCF receives a REGISTER request from a UE served by the P-CSCF, the P-CSCF can include a Resource-Share header field indicating that the P-CSCF supports receiving information about resource sharing.
The example 1 shows the coding when the P-CSCF indicates that the P-CSCF is interested in receiving information about resource sharing in a REGISTER request.
EXAMPLE 1: Resouce-Share: supported |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.9.3 The application server sends information about potential resource sharing to the P-CSCF | When the application server receives a request or response containing an initial SDP offer/answer with media streams subject for resource sharing, the application server includes the Resource-Share header field with the value "media-sharing" and includes a "origin" header field parameter set to "session-initiator" or "session-receiver" depending on if the application server is serving the user that initiated the session invitation or if the application server is serving the user receiving the session invitation.
The application server includes resource sharing information in a "rules" header field parameter with one resource sharing rule per media stream in the same order the corresponding m-line appears in the SDP. Each resource sharing rule is constructed as follows:
1) if the media stream is subject for resource sharing, the application server:
- includes a "new-sharing-key" part;
- if it is the INVITE request and the request will be sent to more than one UE, includes an "existing-resource-sharing-list" part containing one or more sharing keys already in use in other sessions involving UEs that potentially can receive the session invitation due to the forking of the INVITE request; and
- includes a "directionality" part indicating in which direction resources sharing can apply; or
2) if the media stream can never be shared, includes an empty string.
Finally, the application server includes a "timestamp" header field parameter with a value higher than included in any other Resource-Share header field involving any of the UEs registered by the user.
The example 1 shows the Resource-Share header field when included in the initial SDP answer on the originating side. The SDP answer contains two media streams and both media streams are subject to resource sharing.
EXAMPLE 1: Resouce-Share: media-sharing; session-initiator; rules="k1::UL, k20::UL-DL"; timestamp=55688
The example 2 shows the Resource-Share header field when included in the initial SDP offer on the terminating side. The user has several UEs registered where three UEs are already involved in sessions with media streams subject to resource sharing. The SDP offer contains three media streams where only the first and third media stream is subject to resource sharing identified by K2,K3 and K4 for the first media stream and K21, K22 and k23 for the third media stream in already ongoing sessions. The fact that the second media stream is not subject to resource sharing is indicated as an empty string in second position in the comma delimited list of resource sharing rules in the "rules" header field parameter.
EXAMPLE 2: Resouce-Share: media-sharing; session-receiver; rules="k1:k2/k3/k4:UL,, k20:k21/k22/k23:UL-DL"; timestamp=45678
The example 3 shows the Resource-Share header field when included in a SIP request or SIP response on the originating side when an application server indicates that resources can not be shared due to some service specific reason. This indication can be included already from the beginning of the session or at any point during a session if the SIP proxy or UA determines that resource sharing is not possible any longer.
EXAMPLE 3: Resource-Share: no-media-sharing; session-initiator |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.13.9.4 The P-CSCF extracts resource sharing information for media-streams | When the P-CSCF receives an initial SDP answer destined for the served UE in a request or response containing the Resource-Share header field, the P-CSCF extracts the resource sharing rules for each media stream from the "rules" header field parameter in the same order that the corresponding m-line appear in the SDP. The P-CSCF stores and uses the value in the "new-sharing-key" to identify the resource sharing rule for a media stream.
When the P-CSCF receives an initial SDP offer destined for the served UE in a request, the P-CSCF extracts the resource sharing rules for each media stream from the "rules" header field parameter in the same order that the corresponding m-line appear in the SDP. For each extracted resource sharing rule the P-CSCF checks if the UE is involved in any session using a sharing key in the "existing-sharing-key-list" to identify a media-stream, and
- if the UE is involved in a session using a sharing key in the "existing-sharing-key-list" to identify a media-stream, the P-CSCF stores and uses that sharing key value to identify this resource sharing rule for the media stream in this session; or
- if none of the sharing keys in the "existing-sharing-key-list" is used by any session involving the UE or if the "existing-sharing-key-list" is empty, the P-CSCF stores and uses the value in the "new-sharing-key" to identify this resource sharing rule for this media stream in this session.
NOTE: Before storing and using an extracted resource sharing rule the P-CSCF determines the applicability of the rule using the value of the "timestamp" header field parameter as described in subclause 7.2.13.8.4.
If the P-CSCF receives a Resource-Share header field with the value "no-media-sharing" for media streams where resource sharing is already applied due to receipt of a Resource-Share header field with the value "media-sharing" prior to receiving "no-media-sharing" value, the SIP proxy stops media sharing as specified in 3GPP TS 29.214 [13D] annex A. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.14 Definition of Service-Interact-Info header field | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.14.1 Introduction | IANA registry: Header Field Parameter Registry for the Session Initiation Protocol (SIP)
Header field name: Service-Interact-Info
Usage: The Service Interact-Infor header field is used only for informative purposes.
Header field specification reference: 3GPP TS 24.229, http://www.3gpp.org/ftp/Specs/archive/24_series/24.229/
One subscriber can subscribe to one or more services provided by different ASs, and one service may be in conflict with one or more other service. Since the conflict can be subject to the status of the service execution, it cannot be avoided during the service provisioning phase.
To avoid such service conflicts, it is needed to have a mechanism to convey information about services executed between the ASes, and an AS can take such information into account to avoid conflicts when executing the local service logic. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.14.2 Applicability statement for the Service-Interact-Info header field | The Service-Interact-Info header field is applicable within a trust domain. The Service-Interact-Info header field can be included in initial SIP requests and responses to initial SIP requests.
AS can include the service identity which has been executed into the Service-Interact-Info header field and also insert service identities which is in conflict with the already executed service. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.14.3 Usage of the Service-Interact-Info header field | Upon receiving a SIP message and executing service logic, the AS should take the information contained in the Service-Interact-Info header field into account. If
1) the executed services indicated in the Service-Interact-Info header field is in conflict with the local service logic; or
2) the local service logic indicated the Service-Interact-Info header field is inconflict with a previously executed service;
the AS should based on local policy decide whether or not to execute the local service.
When certain service logic has been executed, the AS should include the corresponding service identity into the Service-Interact-Info header field. Additionally, the AS can also include identities of any service which may be in conflicit with the executed service. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.14.4 Procedures at the UA | There are no specific procedures specified for a UA. A UAC in a B2BUA can add a Service-Interact-Info header field into the SIP message, or insert a service identity into the Service-Interact-Info header field, or remove the Service-Interact-Info header field when sending a SIP message |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.14.5 Procedures at the proxy | A SIP proxy that supports this extension can add a Service-Interact-Info header field into a SIP message, insert a service identity into the Service-Interact-Info header field, or remove the Service-Interact-Info header field when forwarding the SIP message. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.14.6 Security considerations | The Service-Interact-Info header field can contain sensitive information. The Service-Interact-Info header field should be removed when sent outside the trust domain.
A UE is not expected to receive the Service-Interact-Info header field. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.14.7 Syntax | The syntax for Service-Interact-Info header field is specified in table 7.2.14-1.
Table 7.2.14-1: Syntax of Service-Interact-Info
Service-Interact-Info = "Service-Interact-Info" HCOLON executed-service-params*(COMMA executed-service-params)
executed-service-params = executed-service / avoid-service
executed-service = "executed-service" EQUAL service-spec
avoid-service = "avoid-service" EQUAL service-spec
service-spec = service-id *(SEMI service-param)
service-id = token/quoted-string
service-param = generic-param |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.15 Definition of Cellular-Network-Info header field | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.15.1 Introduction | A User Agent (UA) supporting one or more cellular radio access technology (e.g. E-UTRAN) but using a non-cellular IP-CAN to access the IM CN subsystem can use this header field to relay information to its service provider about the radio cell identity of the cellular radio access network the UE most recently camped on. For example, a UE making an emergency call using the Evolved Packet Core (EPC) via Untrusted Wireless Local Access Network (WLAN) as IP-CAN to access the IM CN subsystem uses this header field to convey location information to its service provider. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.15.2 Applicability statement for the Cellular-Network-Info header field | The Cellular-Network-Info field is applicable within a trust domain. The Cellular-Network-Info header field can be included in any SIP requests and responses in which the P-Access-Network-Info header field is present. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.15.3 Usage of the Cellular-Network-Info header field | The Cellular-Network-Info header field is populated with the following contents:
1) the access-type field is set to one of "3GPP-GERAN","3GPP-UTRAN-FDD", "3GPP-UTRAN-TDD", "3GPP-E-UTRAN-FDD", "3GPP-E-UTRAN-TDD", "3GPP-E-UTRAN-ProSe-UNR", "3GPP-NR-FDD", "3GPP-NR-TDD", "3GPP-NR-U-FDD", "3GPP-NR-U-TDD", "3GPP-NR-ProSe-L2UNR", "3GPP-NR-ProSe-L3UNR", "3GPP2-1X", "3GPP2-1X-HRPD", "3GPP2-UMB", "3GPP2-1X-Femto" as appropriate to the additional access technology the information is provided about;
2) if the access-type field is set to "3GPP-GERAN", a cgi-3gpp parameter set to the Cell Global Identity obtained from lower layers of the UE. The Cell Global Identity is a concatenation of MCC (3 decimal digits), MNC (2 or 3 decimal digits depending on MCC value), LAC (4 hexadeciaml digits) and CI (as described in 3GPP TS 23.003 [3]. The "cgi-3gpp" parameter is encoded in ASCII as defined in RFC 20 [212];
3) if the access-type field is equal to "3GPP-UTRAN-FDD", or "3GPP-UTRAN-TDD", a "utran-cell-id-3gpp" parameter set to a concatenation of the MCC (3 decimal digits), MNC (2 or 3 decimal digits depending on MCC value), LAC (4 hexadecimal digits) as described in 3GPP TS 23.003 [3] and the UMTS Cell Identity (7 hexadecimal digits) as described in 3GPP TS 25.331 [9A]), obtained from lower layers of the UE. The "utran-cell-id-3gpp" parameter is encoded in ASCII as defined in RFC 20 [212];
4) if the access-type field is equal to "3GPP-E-UTRAN-FDD" or "3GPP-E-UTRAN-TDD", a "utran-cell-id-3gpp" parameter set to a concatenation of the MCC (3 decimal digits), MNC (2 or 3 decimal digits depending on MCC value), Tracking Area Code (4 hexadecimal digits when accessing to EPC and 6 hexadecimal digits when accessing to 5GCN) as described in 3GPP TS 23.003 [3]) and the E-UTRAN Cell Identity (ECI) (7 hexadecimal digits) as described in 3GPP TS 23.003 [3]). The "utran-cell-id-3gpp" parameter is encoded in ASCII as defined in RFC 20 [212];
EXAMPLE: If MCC is 111, MNC is 22, TAC is 33C4 and ECI is 76B4321, then Cellular-Network-Info header field looks like follows: Cellular-Network-Info: 3GPP-E-UTRAN-FDD;utran-cell-id-3gpp=1112233C476B4321
5) if the access-type field is equal to "3GPP-E-UTRAN-ProSe-UNR", a "utran-cell-id-3gpp" parameter set to a concatenation of the MCC (3 decimal digits), MNC (2 or 3 decimal digits depending on MCC value) and the E-UTRAN Cell Identity (ECI) (7 hexadecimal digits) as described in 3GPP TS 23.003 [3] obtained from the ProSe-UE-to-network relay that the UE is connected to as specified in 3GPP TS 24.334 [8ZD]. The "utran-cell-id-3gpp" parameter is encoded in ASCII as defined in RFC 20 [212];
EXAMPLE: If MCC is 111, MNC is 22 and ECI is 76B4321, then Cellular-Network-Info header field looks like follows: Cellular-Network-Info: 3GPP-E-UTRAN-ProSe-UNR;utran-cell-id-3gpp=1112276B4321.
6) if the access-type field is set to "3GPP2-1X", a ci-3gpp2 parameter set to the ASCII representation of the hexadecimal value of the string obtained by the concatenation of SID (16 bits), NID (16 bits), PZID (8 bits) and BASE_ID (16 bits) (see 3GPP2 C.S0005-D [85]) in the specified order. The length of the ci-3gpp2 parameter shall be 14 hexadecimal characters. The hexadecimal characters (A through F) shall be coded using the uppercase ASCII characters. If the UE does not know the values for any of the above parameters, the UE shall use the value of 0 for that parameter. For example, if the SID is unknown, the UE shall represent the SID as 0x0000;
NOTE 1: The SID value is represented using 16 bits as opposed to 15 bits as specified in 3GPP2 C.S0005-D [85].
EXAMPLE: If SID = 0x1234, NID = 0x5678, PZID = 0x12, BASE_ID = 0xFFFF, the ci-3gpp2 value is set to the string "1234567812FFFF".
7) if the access-type field is set to "3GPP2-1X-HRPD", a ci-3gpp2 parameter set to the ASCII representation of the hexadecimal value of the string obtained by the concatenation of Sector ID (128 bits) and Subnet length (8 bits) (see 3GPP2 C.S0024-B [86]) and Carrier-ID, if available, (see 3GPP2 X.S0060 [86B]) in the specified order. The length of the ci-3gpp2 parameter shall be 34 or 40 hexadecimal characters depending on whether the Carrier-ID is included. The hexadecimal characters (A through F) shall be coded using the uppercase ASCII characters;
EXAMPLE: If the Sector ID = 0x12341234123412341234123412341234, Subnet length = 0x11, and the Carrier-ID=0x555444, the ci-3gpp2 value is set to the string "1234123412341234123412341234123411555444".
8) if the access-type field is set to "3GPP2-UMB" 3GPP2 C.S0084-000 [86A], a ci-3gpp2 parameter is set to the ASCII representation of the hexadecimal value of the Sector ID (128 bits) defined in 3GPP2 C.S0084-000 [86A]. The length of the ci-3gpp2 parameter shall be 32 hexadecimal characters. The hexadecimal characters (A through F) shall be coded using the uppercase ASCII characters;
EXAMPLE: If the Sector ID = 0x12341234123412341234123412341234, the ci-3gpp2 value is set to the string "12341234123412341234123412341234".
9) if the access-type field is set to "3GPP2-1X-Femto", a ci-3gpp2-femto parameter set to the ASCII representation of the hexadecimal value of the string obtained by the concatenation of femto MSCID (24 bit), femto CellID (16 bit), FEID (64bit), macro MSCID (24 bits) and macro CellID (16 bits) (3GPP2 X.P0059-200 [86E]) in the specified order. The length of the ci-3gpp2-femto parameter is 36 hexadecimal characters. The hexadecimal characters (A through F) are coded using the uppercase ASCII characters;
10) the cell-info-age parameter indicates the relative time since the information about the cell identity was collected by the UE. The value of the parameter is a number indicating seconds;
NOTE 2: How the UE determines the relative time is up to UE implementation per operator policy or local configuration.
11) if the access-type field is equal to "3GPP-NR-FDD" or "3GPP-NR-TDD", a "utran-cell-id-3gpp" parameter set to a concatenation of the MCC (3 decimal digits), MNC (2 or 3 decimal digits depending on MCC value), Tracking Area Code (6 hexadecimal digits) as described in 3GPP TS 23.003 [3], the NR Cell Identity (NCI) (9 hexadecimal digits) and optionally, the Network Identifier (NID) (11 hexadecimal digits) as specified in 3GPP TS 23.003 [3]. The "utran-cell-id-3gpp" parameter is encoded in ASCII as defined in RFC 20 [212];
NOTE 3: NID is included only if a cellular radio access network the UE most recently camped on is an SNPN identified by a combination of NID, MCC and MNC. The serving network type can be unambiguously deduced from the total length of the "utran-cell-id-3gpp" parameter.
12) if the access-type field is equal to "3GPP-NR-U-FDD" or "3GPP-NR-U-TDD", a "utran-cell-id-3gpp" parameter set to a concatenation of the MCC (3 decimal digits), MNC (2 or 3 decimal digits depending on MCC value), Tracking Area Code (6 hexadecimal digits) as described in 3GPP TS 23.003 [3], the NR Cell Identity (NCI) (9 hexadecimal digits) and optionally, the NID (11 hexadecimal digits) as specified in 3GPP TS 23.003 [3]. The "utran-cell-id-3gpp" parameter is encoded in ASCII as defined in RFC 20 [212]; and
13) if the access-type field is equal to "3GPP-NR-ProSe-L2UNR" or "3GPP-NR-ProSe-L3UNR", a "utran-cell-id-3gpp" parameter set to a concatenation of the MCC (3 decimal digits), MNC (2 or 3 decimal digits depending on MCC value), Tracking Area Code (6 hexadecimal digits) as described in 3GPP TS 23.003 [3] and the NR Cell Identity (NCI) (9 hexadecimal digits) obtained from the 5G ProSe UE-to-network relay UE that the UE is connected to as specified in 3GPP TS 24.554 [8ZI]. The "utran-cell-id-3gpp" parameter is encoded in ASCII as defined in RFC 20 [212]. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.15.4 Procedures at the UA | A UA that supports this extension and is willing to disclose the related parameters may insert the Cellular-Network-Info header field in any SIP request or response in which the P-Access-Network-Info header field is allowed to be present. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.15.5 Procedures at the proxy | A SIP proxy shall not modify the value of the Cellular-Network-Info header field.
A SIP proxy shall remove the Cellular-Network-Info header field when the SIP signaling is forwarded to a SIP server located in an untrusted administrative network domain.
A SIP proxy that is providing services to the UA, can act upon the information present in the Cellular-Network-Info header field value, if present, to provide a different service depending on the network or the location through which the UA is accessing the server.A SIP proxy can determine the age of the cell identity information from the cell-info-age parameter. Depending on the recentness of the information the SIP proxy can perform different procedures. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.15.6 Security considerations | The Cellular-Network-Info header field contains sensitive information. The Cellular-Network-Info header field should be removed when sent outside the trust domain.
A UE is not expected to receive the Cellular-Network-Info header field. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.15.7 Syntax | The syntax for Cellular-Network-Info header field is specified in table 7.2.15-1.
Table 7.2.15-1: Syntax of Cellular-Network-Info
Cellular-Network-Info = "Cellular-Network-Info" HCOLON cellular-net-spec
cellular-net-spec = access-type *(SEMI cellular-access-info)
access-type = "3GPP-GERAN" / "3GPP-UTRAN-FDD" / "3GPP-UTRAN-TDD" /
"3GPP-E-UTRAN-FDD" / "3GPP-E-UTRAN-TDD" / "3GPP2-1X-Femto" /
"3GPP2-UMB" / "3GPP2-1X-HRPD" / "3GPP2-1X" /
"3GPP-E-UTRAN-ProSe-UNR" / "3GPP-NR-FDD" / "3GPP-NR-TDD" /
"3GPP-NR-U-FDD" / "3GPP-NR-U-TDD" /
"3GPP-NR-ProSe-L2UNR" / "3GPP-NR-ProSe-L3UNR" /
token
cellular-access-info = access-info / cell-info-age
access-info = cgi-3gpp / utran-cell-id-3gpp /
ci-3gpp2 / ci-3gpp2-femto / extension-access-info
extension-access-info = generic-param
cgi-3gpp = "cgi-3gpp" EQUAL (token / quoted-string)
utran-cell-id-3gpp = "utran-cell-id-3gpp" EQUAL (token / quoted-string)
ci-3gpp2 = "ci-3gpp2" EQUAL (token / quoted-string)
ci-3gpp2-femto = "ci-3gpp2-femto" EQUAL (token / quoted-string)
cell-info-age = "cell-info-age" EQUAL 1*9DIGIT |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.16 Priority-Share header field | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.16.1 Introduction | IANA registry: Header Field Parameter Registry for the Session Initiation Protocol (SIP)
Header field name: Priority-Share
Usage: The Priority-Share header field is used only for informative purposes.
Header field specification reference: 3GPP TS 24.229, http://www.3gpp.org/ftp/Specs/archive/24_series/24.229/
The Priority-Share header field is used to carry information relating to the possibility to use priority sharing. Priority sharing allows the P-CSCF to instruct the access gateway to use the same bearer for several sessions regardless of the priority of the sessions. When priority sharing is not allowed the P-CSCF will instruct the access gateway to not use priority sharing. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.16.2 Applicability statement for the Priority-Share header field | The Priority-Share header field is applicable within a single private administrative domain or between different administrative domains where there is a trust relationship between the domains.
The Priority-Share header field is not included in a SIP message sent to another network if there is no trust relationship.
The Priority-Share header field is applicable whenever an application/sdp MIME body would be applicable, as defined by RFC 3261 [26]. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.16.3 Usage of the Priority-Share header field | A SIP UA or SIP proxy that receives a SIP request or response that contains a Priority-Share header field can use the values as appropriate.
A SIP proxy may remove the Priority-Share header field according to local policy. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.16.4 Procedures at the UA | An application server acting as a UA that supports this extension and receives a request or response without the Priority-Share header field may insert a Priority-Share header field prior to forwarding the message. The header is populated as described in subclause 7.2.16.7.
If an application server acting as a UA that supports this extension receives a request or response with the Priority-Share header field, it may use the information from the header field for application-specific logic, i.e., resource reservation. If information from the header field is used, the header field shall be removed from the request or response. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.16.5 Procedures at the proxy | A SIP proxy that supports this extension and receives a request or response without the Priority-Share header field may insert a Priority-Share header field prior to forwarding the message. The header is populated as described in subclause 7.2.16.7.
If a proxy that supports this extension receives a request or response with the Priority-Share header field, it may use the information from the header field for application-specific logic, i.e., resource reservation. If information from the header field is used, the header field shall be removed from the request or response. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.16.6 Security considerations | The Priority-Share header field does not contain any information that can disclose user information or the topology of nodes within an operator network. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.16.7 Syntax | The syntax for Priority-Share header field is specified in table 7.2.16.1
Table 7.2.16.1: Syntax of Priority-Share
priority-share = "Priority-Share" HCOLON priority-share-options *( SEMI generic-param)
priority-share-options = "allowed" / "not-allowed" / other-options
other-options = token |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.16.8 Examples of usage | The Priority-Share header field is included by an application server in the home network to inform about the possibility to share resources between session regardless of the priority of a session. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.17 Definition of Response-Source header field | |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.17.1 Introduction | IANA registry: Header Fields registry for the Session Initiation Protocol (SIP)
Header field name: Response-Source
Usage: the Response-Source header field is used only for informative purposes.
Header field specification reference: 3GPP TS 24.229, http://www.3gpp.org/ftp/Specs/archive/24_series/24.229/
The Response-Source header field is used to carry information related to the originator of an error response. The receiving entities may possibly use this information to decide a more appropriate procedure to invoke in regards with the failure response. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.17.2 Applicability statement for the Response-Source header field | The Response-Source header field is applicable within a single private administrative domain or between different administrative domains where there is a trust relationship between the domains. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.17.3 Usage of the Response-Source header field | A SIP UA or SIP proxy may include the Response-Source header field when responding to a SIP request with an error response to provide the information on who is the sender of the error response using the appropriate URN value as defined in subclause 7.2.17.7.
A SIP UA or SIP proxy that receives a SIP response that contains a Response-Source header field can use the values as appropriate. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.17.4 Procedures at the UA | A UA that supports this extension and rejects a request with an error response may insert a Response-Source header field within the response message. The header is populated as described in subclause 7.2.17.7.
If a UA that supports this extension receives a response with the Response-Source header field, it may take the information from the Response-Source header field into account when handling the response.
NOTE: The Response-Source header field is informational. A UA receiving a response containing a Response-Source header field does not perform any action contrary to the behavior specified in RFC 3261 [26] or other RFCs that specify UA actions upon receiving the specific response code. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.17.5 Procedures at the proxy | A proxy that supports this extension and receives a request for which its internal logic leads to reject the request with an error response may insert a Response-Source header field within the response message. The header is populated as described in subclause 7.2.17.7.
If a proxy that supports this extension receives a response with the Response-Source header field, it may use the information from the header field for its internal logic for error reponses handling. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.17.6 Security considerations | The Response-Source header field will contain a URN identifying the sender that may be considered as sensitive information. The Response-Source header field may be removed when received from outside the trust domain depending on the network policy. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.17.7 Syntax | The ABNF syntax for Response-Source header field is specified in table 7.2.17.7-1.
Table 7.2.17.7-1: Syntax of Response-Source header field
Response-Source = "Response-Source" HCOLON source-info
source-info = source-params *(SEMI source-params)
source-params = source-urn / token
source-urn = "fe" EQUAL LAQUOT source-urn-val RAQUOT
source-urn-val = 1*uric ; defined in RFC 3261
The source-urn-val of the source-urn parameter is coded as a URN. The URN identifies the SIP capable functional entity sending a SIP response.
A URN is defined under the "urn:3gpp" label defined in RFC 5279 [253].
The extension of 3gpp-urn is:
urn:3gpp:fe
A formal reference to the publicly available specification:
3GPP TS 24.229
A short phrase describing the function of the extension:
The namespace "fe" is for indicating an IMS functional-entity. See the coding for the namespace extension ns-ext in table 7.2.17.7-2:
Table 7.2.17.7-2: Syntax of urn:3gpp:fe
ns-ext = HCOLON "fe" HCOLON functional-entity
functional-entity = fe-id *("." fe-param)
fe-id = "ue" / "p-cscf" / "i-cscf" / "s-cscf" / "e-cscf" / "mgcf" / "bgcf" / "ibcf" / "trf" / "atcf" / "agcf" / "mrfc" / "lrf" / "msc-server" / "as" / token
fe-param = role / side / token
role = "tas" / "scc-as" / "ip-sm-gw" / "pf-mcptt-server" / "cf-mcptt-server" / "ncf-mcptt-server" / "cms" / "gms" / "tads" / "iua" / "msc-server-ics" / token
side = "orig" / "term" / "transit"/ token
Contact information for the organization or person making the registration
3GPP Specifications Manager
[email protected]
+33 (0)492944200
The following fe-id values are defined:
- ue: represents the UE;
- p-cscf: represents the P-CSCF;
- i-cscf: represents the I-CSCF;
- s-cscf: represents the S-CSCF;
- e-cscf: represents the E-CSCF;
- mgcf: represents the MGCF;
- bgcf: represents the BGCF;
- ibcf: represents the IBCF;
- trf: represents the TRF;
- atcf: represents the ATCF;
- agcf: represents the AGCF;
- mrfc: represents the MRFC;
- lrf: represents the LRF;
- msc-server: represents the MSC server; and
- as: represents the AS.
The following fe-param values are defined:
- role:
a. mmtel-as: indicates that the AS is performing the MMTel services role;
b. scc-as: indicates that the AS is performing the SCC AS role;
c. ip-sm-gw: indicates that the AS is performing the IP-SM-GW role;
d. pf-mcptt-server: indicates that the AS is performing the participating MCPTT server role;
e. cf-mcptt-server: indicates that the AS is performing the controling MCPTT server role;
f. ncf-mcptt-server: indicates that the AS is performing the non-controling MCPTT server role;
g. cms: indicates that the AS is performing the configuration management server role;
h. gms: indicates that the AS is performing the group management server role;
i. tads: indicates that the AS is performing the terminating access domain selection role;
j. iua: indicates that the AS is performing the ICS User Agent role; and
k. msc-server-ics: indicates that the MSC is performing the MSC server enhanced for ICS role.
- side:
a. orig: indicates that this functional entity is in the originating network;
b. term: indicates that this functional entity is in the terminating network;and
c. transit: indicates that this functional entity is in a transit network.
An example of the source-urn header field parameter value is: fe=<urn:3gpp:fe:p-cscf.orig>. |
d3a3ac3f64ab68e4fcef5ea9a665f70a | 24.229 | 7.2.18 Definition of Attestation-Info header field |
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