18 Inter-UE transfer (IUT)
29.1653GPPInter-IMS Network to Network Interface (NNI)Release 18TS
18.1 General
Inter-UE transfer may be supported over the II-NNI. The IUT consist of several functional blocks, as described in the clauses below. The support of each of these functional blocks is based on agreement between operators.
If a function is supported, the related procedures from the 3GPP TS 24.337 [149] shall be applied with the requirements in the relevant clause below.
18.2 IUT without establishment of a collaborative session
Service specific requirements in accordance with 3GPP TS 24.337 [149] shall be supported over the II-NNI.
The REFER request shall be supported at the roaming II-NNI.
The Refer-To header field containing a body parameter including a Replaces header field and the Require header field set to "replaces" shall be supported at the roaming II-NNI.
The Refer-To header field containing a body parameter including a Target-Dialog header field and the Require header field set to "tdialog" shall be supported at the roaming II-NNI.
The Refer-To header field containing a body parameter including an Accept-Contact header field with the "g.3gpp.icsi-ref" media feature tag and a P-Preferred-Service header field set to the IMS communication service identifier shall be supported at the roaming II-NNI.
The Contact header field of the REFER request containing a public GRUU or temporary GRUU as specified in 3GPP TS 24.229 [5] shall be supported at the roaming II-NNI.
The "g.3gpp.icsi-ref" media feature tag in the Accept-Contact header field of the REFER request shall be supported at the roaming II-NNI.
NOTIFY requests containing a "sipfrag" MIME body as specified in IETF RFC 3515 [22], using the updated procedures from IETF RFC 6665 [20], shall be supported at the roaming II-NNI.
18.3 IUT using a collaborative session
18.3.1 Collaborative session of participants of the same subscription
This clause describes the requirements at the II-NNI for an ongoing session. Service specific requirements in accordance with 3GPP TS 24.337 [149] shall be supported over the II-NNI.
The "g.3gpp.iut-controller" media feature tag in the Accept-Contact header field in the REGISTER request shall be supported.
A REFER request sent outside an existing dialog shall be supported at the roaming II-NNI with the following additional requirements:
– The Refer-To header field containing a body parameter including a MIME sdp body and no method parameter, the method parameter set to "INVITE" or "BYE" shall be supported at the roaming II-NNI.
– The Accept header field containing the MIME type "message/sipfrag" in the REFER request shall be supported at the roaming II-NNI.
– The Target-Dialog header field in the REFER request shall be supported at the roaming II-NNI.
– The Contact header field in the REFER request containing the "g.3gpp.iut-controller" media feature tag as described in annex B of 3GPP TS 24.337 [149] shall be supported at the roaming II-NNI.
– The Contact header field in the REFER request containing the "g.3gpp current-iut-controller" media feature tag as described in annex B of 3GPP TS 24.337 [149] shall be supported at the roaming II-NNI.
– The "g.3gpp.iut-controller" media feature tag in the Accept-Contact header field shall be supported at the roaming II-NNI.
– The Referred-By header field shall be supported at the roaming II-NNI at the roaming II-NNI.
The NOTIFY request containing a "sipfrag" MIME body as specified in IETF RFC 3515 [22], using the updated procedures from IETF RFC 6665 [20], shall be supported at the roaming II-NNI.
Initial INVITE requests and re-INVITE requests as follows:
– The Referred-By header field included in initial INVITE requests and re-INVITE requests shall be supported at the roaming II-NNI;
– The "g.3gpp.iut-controller" media feature tag as described in annex B of 3GPP TS 24.337 [149] in the Contact header field shall be supported at the roaming II-NNI.
The "g.3gpp.iut-controller" media feature tag in responses to the INVITE request shall be supported at the roaming II-NNI.
The SUBSCRIBE request including the Event header field with the "dialog" event package; and including the Accept-Contact header field with the "g.3gpp.iut-focus" media feature shall be supported at the roaming II-NNI.
The "dialog-info+xml" MIME body in NOTIFY requests shall be supported at the roaming II-NNI.
18.3.2 Establishment of a collaborative session during session setup
Service specific requirements in accordance with 3GPP TS 24.337 [149] shall be supported over the II-NNI.
The Accept header field containing the MIME type "application/vnd.3gpp.iut+xml" in initial INVITE requests shall be supported at the roaming II-NNI.
A Content-Type header field containing the MIME type "application/vnd.3gpp.iut+xml" and an "application/vnd.3gpp.iut+xml" MIME body in the 300 (Multiple Choices) response shall be supported at the roaming II-NNI.
18.3.3 Assignment and transfer of control of a collaborative session
Service specific requirements in accordance with 3GPP TS 24.337 [149] shall be supported over the II-NNI.
The "g.3gpp current-iut-controller" media feature tag in the Contact header field of the 200 (OK) response to INVITE request shall be supported at the roaming II-NNI.
A "multipart/mixed" MIME body containing the "application/vnd.3gpp.iut+xml" and the "application/sdp" MIME bodies in the INVITE request shall be supported at the roaming II-NNI.
18.3.4 Collaborative session of participants of different subscriptions
Service specific requirements in accordance with 3GPP TS 24.337 [149] shall be supported over the II-NNI.
In addition to the requirements in clause 18.3.1, 18.3.2 or 18.3.3 the following applies:
– The "g.3gpp.iut-focus" media feature tag (specified in 3GPP TS 24.337 [149] annex B) in the Contact header field shall be supported at the non-roaming II-NNI and for the loopback traversal scenario.
– The "+g.3gpp.iut-focus" header field parameter (specified in 3GPP TS 24.337 [149] annex B) in the Feature-Caps header field as described in IETF RFC 6809 [143] shall be supported at the non-roaming II-NNI and for the loopback traversal scenario.
18.4 Session replication / media replication
18.4.1 Pull mode
Service specific requirements in accordance with 3GPP TS 24.337 [149] shall be supported over the II-NNI.
The Target-Dialog header field and the Accept-Contact header field containing the "g.3gpp.iut-focus" media feature tag of the INVITE request shall be supported at the roaming II-NNI.
A REFER request including:
– the method parameter set to "MESSAGE" in the Refer-To header field;
– the In-Reply-To header field;
– the Target-Dialog header field;
– the Require header field populated with the option tag value "tdialog"; and
– the "application/vnd.3gpp.replication+xml" MIME body,
shall be supported at the roaming II-NNI.
A MESSAGE request including the In-Reply-To header field and the "application/vnd.3gpp.replication+xml" MIME body shall be supported at the roaming II-NNI.
18.4.2 Push mode
Service specific requirements in accordance with 3GPP TS 24.337 [149] shall be supported over the II-NNI.
A REFER request including:
– the Accept-Contact header field containing the "g.3gpp.iut-focus" media feature tag with explicit and require tags;
– the Target-Dialog header field; and
– the Refer-To header field containing the Accept-Contact header field, the P-Preferred-Service header field and the "application/sdp" MIME body,
shall be supported at the roaming II-NNI.
The "application/vnd.3gpp.replication+xml" MIME body of the REFER request shall be supported at the roaming II-NNI.