24.4103GPPCommunication HOLD (HOLD) PSTN/ISDN simulation servicesNGN Signalling Control ProtocolProtocol specificationRelease 8TISPANTS

Assumption is that a session has been established between UE-A and UE-B using basic communication procedures according to ES 283 003 [1], therefore the following signalling flows do not apply to the initial INVITE.

A.1.1 HOLD communication without announcement

The following diagram shows a communication session put on hold using a reINVITE request, note that the same can be achieved by sending an UPDATE request.

Figure A.1.1.1: HOLD communication without announcement to the held user

1. UE-A sends an INVITE to UE-B to hold the session. Hold is done by changing the SDP attribute:

• "a=sendonly", if the stream was previously a sendrecv media stream;
• "a=inactive", if the stream was previously a recvonly media stream.

A.1.2 HOLD communication with announcement

The following diagram shows a communication session put on hold using a reINVITE request, note that the same can be achieved by sending an UPDATE request.

Figure A.1.2.1: HOLD communication with announcement to the held user

1. UE-A sends an INVITE to UE-B to hold the session. Hold is done by changing the SDP attribute:

• "a=sendonly", if the stream was previously a sendrecv media stream;
• "a=inactive", if the stream was previously a recvonly media stream.