The present document specifies the Broadcast Call Control (BCC) protocol used by the Voice Broadcast Call Service (VBCS) on the radio interface.

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.

• References are either specific (identified by date of publication, edition number, version number, etc.) or non specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.

Support of the broadcast call protocol is optional in the MS and in the network.

The present document describes the broadcast call control (BCC) protocol, which is one of the protocols of the Connection Management (CM) sublayer (see TS 24.007). There is in general more than one MS engaged in a broadcast call. Consequently, there is in general more than one MS with a BCC entity engaged in the same broadcast call, and there is one BCC entity in the network engaged in that broadcast call. Under which conditions a BCC message is passed from lower (sub )layers to the BCC entity is defined in the specifications of the sub layers. The MS shall ignore BCC messages that it receives which were sent in unacknowledged mode and which explicitly specify as destination a mobile identity which is not a mobile identity of the MS. Higher layers and the MM sub layer decide when to accept parallel BCC transactions and when/whether to accept BCC transactions in parallel to other CM transactions. The broadcast call may be initiated by a mobile user or by a dispatcher. Specification of a protocol for dispatchers is out of the scope of the present document. Hence, in the scope of the present document, there are:

• one BCC entity in the network; and
• one or more than one BCC entities in different MSs;

engaged in a broadcast call, and one ore none of the MSs is the originator of the broadcast call (called the originating MS in the present document). The originator of the BCC transaction chooses the Transaction Identifier (TI). A MS not assuming to be the originator of the transaction will chose the transaction identifier received from the network, setting the TI flag to 1+x mod 2 where x is the received TI flag. The present document describes the broadcast call control protocol only with regard to two peer entities, one in a MS, the other one in the network. The call control entities are described as communicating finite state machines which exchange messages across the radio interface and communicate internally with other protocol (sub)layers. In particular, the BCC protocol uses the MM and RR sublayer specified in TS 24.008 and TS 44.018. The BCC entity in a MS that is not the originator of the broadcast call shall not send messages to its peer entity. This description in only normative as far as the consequential externally observable behaviour is concerned. For simplicity, instead of using the terms "BCC entity in the MS" and "BCC entity in the network", the present document often uses the terms "MS" and "network" if no confusion may arise. Certain sequences of actions of the two peer entities compose "elementary procedures" which are used as a basis for the description in the present document. These elementary procedures are defined in clause 6. The network should apply supervisory functions to verify that the BCC procedures are progressing and if not, take appropriate means to resolve the problems. This, however, is out of the scope of the present document.