H.2 DOCSIS aspects when connected to the IM CN subsystem

24.2293GPPIP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP)Release 18Stage 3TS

H.2.1 Introduction

A UE accessing the IM CN subsystem, and the IM CN subsystem itself, utilise the services provided by the DOCSIS cable access network to provide packet-mode communication between the UE and the IM CN subsystem.

From the perspective of the UE, the necessary IP-CAN bearer for signalling is transparently available to the UE.

The UE is not directly involved in requests for IP-CAN bearer(s) for media flow(s). The IM CN interacts with the PCRF in the DOCSIS IP-CAN to establish IP-CAN bearer(s) for media flow(s), on behalf of the UE.

H.2.2 Procedures at the UE

H.2.2.1 Activation and P-CSCF discovery

Prior to communication with the IM CN subsystem, the UE shall perform a Network Attachment procedure as defined in the CableLabs PacketCable specifications PKT-TR-ARCH-FRM [88]. When using DOCSIS, both IPv4 and IPv6 UEs may access the IM CN subsystem. The procedures for P-CSCF discovery defined in subclause 9.2.1 of this document apply.

H.2.2.1A Modification of IP-CAN used for SIP signalling

Not applicable.

H.2.2.1B Re-establishment of the IP-CAN used for SIP signalling

Not applicable.

H.2.2.1C P-CSCF restoration procedure

A UE supporting the P-CSCF restoration procedure uses the keep-alive procedures described in RFC 6223 [143].

If the P-CSCF fails to respond to the keep-alive request the UE shall acquire a different P-CSCF address using any of the methods described in the subclause H.2.2.1 and perform an initial registration as specified in subclause 5.1.

H.2.2.2 Void

H.2.2.3 Void

H.2.2.4 Void

H.2.2.5 Handling of the IP-CAN for media

H.2.2.5.1 General requirements

The UE does not directly request resources for media flow(s).

H.2.2.5.1A Activation or modification of IP-CAN for media by the UE

Not applicable.

H.2.2.5.1B Activation or modification of IP-CAN for media by the network

Not applicable.

H.2.2.5.1C Deactivation of IP-CAN for media

Not applicable.

H.2.2.5.2 Special requirements applying to forked responses

The UE does not directly request resources for media flow(s). As a result there are no special UE requirements applying to forked responses.

H.2.2.5.3 Unsuccessful situations

Not applicable.

H.2.2.6 Emergency service

H.2.2.6.1 General

If attached to network via DOCSIS access technology, the UE shall always consider being attached to its home operator’s network for the purpose of emergency calls.

NOTE: In DOCSIS the UE is unable to receive any indication from the network, that would allow the UE to determine, whether it is currently attached to its home operator’s network or to a different network, so the UE assumes itself always attached to the home operator’s network when connected via DOCSIS access technology.

H.2.2.6.1A Type of emergency service derived from emergency service category value

Not applicable.

H.2.2.6.1B Type of emergency service derived from extended local emergency number list

Not applicable.

H.2.2.6.2 eCall type of emergency service

The UE shall not send an INVITE request with Request-URI set to "urn:service:sos.ecall.manual" or "urn:service:sos.ecall.automatic".

H.2.2.6.3 Current location discovery during an emergency call

Void.

H.2A Usage of SDP

H.2A.0 General

Not applicable.

H.2A.1 Impact on SDP offer / answer of activation or modification of IP-CAN for media by the network

Not applicable.

H.2A.2 Handling of SDP at the terminating UE when originating UE has resources available and IP-CAN performs network-initiated resource reservation for terminating UE

Not applicable.

H.2A.3 Emergency service

No additional procedures defined.