A.10 Retrieval of network provided location information

29.2143GPPPolicy and charging control over Rx reference pointRelease 17TS

A.10.1 General

According to Annex E.7 of 3GPP TS 23.228 [16], the P-CSCF can use PCC to retrieve network provided location information. Information flows related to the distribution of network provided location information within the IMS are provided in Annex R of 3GPP TS 23.228 [16].

This sublause provides optional PCC procedures to support the retrieval of network provided location information.

The originating P-CSCF can, depending on operator policy, retrieve the user location and/or UE Time Zone information either before sending the INVITE or MESSAGE towards the terminating side or upon reception of the SDP answer from the terminating side.

The terminating P-CSCF can, depending on operator policy, retrieve the user location and/or UE Time Zone information either upon reception of a SIP INVITE or upon reception of a SIP response.

The originating and terminating P-CSCF can, depending on operator policy, retrieve the user location and/or UE Time Zone information at mid call, e.g., when the P-CSCF learns about IP-CAN type change.

A.10.2 Retrieval of network provided location information at originating P-CSCF for inclusion in SIP Request

If the originating P-CSCF is required by operator policy to retrieve network provided location information before forwarding a SIP INVITE request, upon reception of an INVITE/UPDATE request, the P-CSCF shall send an AA-Request according to clause 4.4.1 (SIP INVITE request) or 4.4.2 (SIP INVITE/UPDATE request) including:

– the "ACCESS_NETWORK_INFO_REPORT" value within the Specific-Action AVP; and

– the required access network information within the Required-Access-Info AVP.

If the SIP INVITE request is an initial SIP INVITE request, the P-CSCF shall establish an Rx session for the new SIP session with the AA-Request according to clause 4.4.6.7 (if no session information is included) or 4.4.1 (if preliminary session information is included).

The P-CSCF will receive the access network information from the PCRF in an RAR, and should include this access network information in the SIP INVITE/UPDATE requests that it forwards. When the retrieved access network information corresponds to the TWAN-Identifier AVP, the P-CSCF may also map the retrieved access network information to a Geographical Identifier for routing, as specified in Annex E.8 of 3GPP TS 23.228 [16].

A.10.3 Retrieval of network provided location information at originating P-CSCF for inclusion in SIP response confirmation

If an originating P-CSCF is required by operator policy to retrieve network provided location information before forwarding an SDP answer, the P-CSCF shall apply the following procedures:

Upon reception of an SDP offer, the P-CSCF may send an AA-Request to the PCRF according to clause A.1 and may include in this AA-request:

– the "ACCESS_NETWORK_INFO_REPORT" value within the Specific-Action AVP; and

– the required access network information within the Required-Access-Info AVP.

Upon reception of an SDP answer, the P-CSCF will send an AA-Request to the PCRF according to clause A.1. If the P-CSCF has not requested access network information upon reception of the SDP offer, the P-CSCF shall include in this AA-request:

– the "ACCESS_NETWORK_INFO_REPORT" value within the Specific-Action AVP; and

– the required access network information within the Required-Access-Info AVP.

The P-CSCF will receive the access network information from the PCRF in an RAR, and should include this access network information in the SIP message with the response confirmation before forwarding it. When the retrieved access network information corresponds to the TWAN-Identifier AVP, the P-CSCF may also map the retrieved access network information to a Geographical Identifier for routing, as specified in Annex E.8 of 3GPP TS 23.228 [16].

If the originating P-CSCF is required by operator policy to retrieve network provided location information before forwarding a SIP MESSAGE request, upon reception of a MESSAGE request, the P-CSCF shall send an AA-Request including:

– the UE’s IP address (using either the Framed-IP-Address AVP or the Framed-Ipv6-Prefix AVP);

– a Media-Component-Description AVP including a single Media-Sub-Component AVP with the Flow-Usage AVP set to the value "AF_SIGNALLING". The Media-Component-Description AVP shall contain the Media-Component-Number AVP set to "0". The Media-Sub-Component AVP shall contain the Flow-Number AVP set to "0", and the rest of AVPs within the Media-Component-Description and Media-Sub-Component AVPs shall not be used in this case;

– the "ACCESS_NETWORK_INFO_REPORT" value within the Specific-Action AVP; and

– the required access network information within the Required-Access-Info AVP.

The P-CSCF will receive the access network information from the PCRF in an RAR and should include this access network information in the SIP MESSAGE requests that it forwards. When the retrieved access network information corresponds to the TWAN-Identifier AVP, the P-CSCF may also map the retrieved access network information to a Geographical Identifier for routing, as specified in Annex E.8 of 3GPP TS 23.228 [16].

If the Rx Diameter Session is only used for retrieval of network provided location information, at reception of this information, the AF may terminate the AF session sending a Session-Termination-Request (STR) command to the PCRF, which shall be acknowledged with a Session-Termination-Answer (STA) command.

A.10.4 Retrieval of network provided location information at terminating P-CSCF

If a terminating P-CSCF is required by operator policy to retrieve network provided location information at session establishment and/or modification, the P-CSCF shall apply the following procedures:

The terminating P-CSCF may request network provided location information upon reception of a SIP INVITE request : in the following manner:

– If the SIP INVITE request is an initial SIP INVITE request, the P-CSCF shall establish an Rx session for the new SIP session with the AA-Request according to clause 4.4.6.7 (if no session information is included) or 4.4.1 (if preliminary session information is included).

– If the SIP INVITE includes an SDP offer, the P-CSCF shall send an AA-Request including:

– the "ACCESS_NETWORK_INFO_REPORT" value within the Specific-Action AVP;

– the required access network information within the Required-Access-Info AVP;

– service information derived from the SDP offer; and

– the Service-Info-Status AVP with the value set to PRELIMINARY SERVICE INFORMATION.

– If the SIP INVITE includes no SDP offer, the P-CSCF shall send an AA-Request including:

– the "ACCESS_NETWORK_INFO_REPORT" value within the Specific-Action AVP; and

– the required access network information within the Required-Access-Info AVP.

Upon reception of a SIP response that requires the inclusion of access network information, if the P-CSCF has not already requested network provided location information upon reception of the corresponding SIP INVITE, the P-CSCF shall request network provided location information in the following manner:

– If an Rx session related to service data has not yet been established, the P-CSCF shall establish an Rx session for the new SIP session with the AA-Request according to clause 4.4.6.7 (if no session information is included) or 4.4.1 (if session information is included).

– If the SIP response includes an SDP answer, the P-CSCF will send an AA-Request to the PCRF according to clause A.1; the P-CSCF shall include in this AA-request:

– the "ACCESS_NETWORK_INFO_REPORT" value within the Specific-Action AVP; and

– the required access network information within the Required-Access-Info AVP.

– If the SIP response includes no SDP, the P-CSCF shall send an AA-Request including:

– the "ACCESS_NETWORK_INFO_REPORT" value within the Specific-Action AVP; and

– the required access network information within the Required-Access-Info AVP.

– If the SIP reponse includes an SDP offer, the P-CSCF shall send an AA-Request including:

– the "ACCESS_NETWORK_INFO_REPORT" value within the Specific-Action AVP;

– the required access network information within the Required-Access-Info AVP;

– service information derived from an SDP offer within the SIP response; and

– the Service-Info-Status AVP with the value set to PRELIMINARY SERVICE INFORMATION.

The P-CSCF will receive the access network information from the PCRF in an RAR, and should include this access network information in the appropriate SIP response before forwarding it. When the retrieved access network information corresponds to the TWAN-Identifier AVP, the P-CSCF may also map the retrieved access network information to a Geographical Identifier for routing, as specified in Annex E.8 of 3GPP TS 23.228 [16].

If the terminating P-CSCF is required by operator policy to retrieve network provided location information upon reception of a SIP MESSAGE response, the P-CSCF shall behave according to A.10.2.

A.10.5 Provisioning of network provided location information at SIP session release

If a P-CSCF is required by operator policy to include network provided location information in SIP session release signalling, the P-CSCF shall apply the following procedures:

Upon reception of a SIP session release request that requires the inclusion of network provided location information, the P-CSCF will send an ST-Request and shall include in this request the required access network information within the Required-Access-Info AVP.

The P-CSCF will receive the access network information from the PCRF in the corresponding ST-Answer, and should include this access network information either in the SIP session termination request (at the originating side) or a reply to the SIP session termination request (at the terminating side). When the retrieved access network information corresponds to the TWAN-Identifier AVP, the P-CSCF may also map the retrieved access network information to a Geographical Identifier for routing, as specified in Annex E.8 of 3GPP TS 23.228 [16].

A.10.6 Provisioning of network provided location information at mid call

If a P-CSCF is required by operator policy to include network provided location information at mid call, the P-CSCF shall apply the following procedures:

Upon reception of a trigger (e.g., when the P-CSCF learns about the access change) that requires the inclusion of network provided location information in a SIP message, the P-CSCF shall include in the AA-request:

– the "ACCESS_NETWORK_INFO_REPORT" value within the Specific-Action AVP;

– the required access network information within the Required-Access-Info AVP; and

– the service information related to the service according to clause 4.4.2.

The P-CSCF will receive the access network information from the PCRF in an RAR, and should include this access network information in the appropriate SIP message before forwarding it. When the retrieved access network information corresponds to the TWAN-Identifier AVP, the P-CSCF may also map the retrieved access network information to a Geographical Identifier for routing, as specified in Annex E.8 of 3GPP TS 23.228 [16].