6.4 Implicit floor request

24.3793GPPMission Critical Push To Talk (MCPTT) call controlProtocol specificationRelease 18TS

An initial SIP INVITE request fulfilling the following criteria shall be regarded by the MCPTT server as an implicit floor request by the originating MCPTT client when the MCPTT client:

1) initiates an MCPTT speech session or initiates a pre-established session that is not used for a remotely initiated MCPTT ambient listening call; and

2) includes the "mc_implicit_request" ‘fmtp’ attribute in the associated UDP stream for the floor control in the SDP offer/answer as specified in 3GPP TS 24.380 [5] clause 12.

An initial SIP INVITE request fulfilling the following criteria shall be regarded by the MCPTT server as an implicit request to grant the floor to the terminating MCPTT client when the originating MCPTT client:

1) initiates a remotely initiated MCPTT ambient listening call; and

2) includes the "mc_implicit_request" ‘fmtp’ attribute in the associated UDP stream for the floor control in the SDP offer/answer as specified in 3GPP TS 24.380 [5] clause 12.

A SIP re-INVITE request fulfilling the following criteria shall be regarded by the MCPTT server as an implicit floor request when the MCPTT client:

1) performs an upgrade of:

a) an MCPTT group call to an emergency MCPTT group call;

b) an MCPTT private call to an emergency MCPTT private call; or

c) an MCPTT group call to an imminent peril MCPTT group call; and

2) includes the "mc_implicit_request" ‘fmtp’ attribute in the associated UDP stream for the floor control in the SDP offer/answer as specified in 3GPP TS 24.380 [5] clause 12.

In all other cases the SIP (re-)INVITE request shall be regarded as received without an implicit floor request.

When using a pre-established session the MCPTT server shall regard the SIP REFER request as an implicit floor request:

1) if the pre-established session was established with an implicit floor request and if an SDP offer is not included in a "body" parameter in the headers portion of the SIP URI in a "uri" attribute of an <entry> element of a <list> element of the <resource-lists> element of the application/resource-lists+xml MIME body, referenced by the "cid" URL in the Refer-To header field;

2) if the pre-established session was established with an implicit floor request, an SDP offer is included in a "body" parameter in the headers portion of the SIP URI in a "uri" attribute of an <entry> element of a <list> element of the <resource-lists> element of the application/resource-lists+xml MIME body, referenced by the "cid" URL in the Refer-To header field, and this SDP includes the "mc_implicit_request" media level attribute in the associated UDP stream for the floor control in the SDP offer; or

3) if the pre-established session was established without an implicit floor request and the SDP offer in a "body" parameter in the headers portion of the SIP URI in a "uri" attribute of an <entry> element of a <list> element of the <resource-lists> element of the application/resource-lists+xml MIME body, referenced by the "cid" URL in the Refer-To header field includes the "mc_implicit_request" media level attribute in the associated UDP stream for the floor control in the SDP offer.

In all other cases the SIP REFER request shall be regarded as received without an implicit floor request.

When using a pre-established session the MCPTT server shall regard the SIP REFER request as an implicit request to grant the floor to the terminating MCPTT client:

1) if the pre-established session was established with an SDP offer included in a "body" parameter in the headers portion of the SIP URI in a "uri" attribute of an <entry> element of a <list> element of the <resource-lists> element of the application/resource-lists MIME+xml body, referenced by the "cid" URL in the Refer-To header field, and this SDP includes the "mc_implicit_request" media level attribute in the associated UDP stream for the floor control in the SDP offer; and

2) the pre-established session is being used for a remotely initiated ambient listening call.

In all other cases the SIP REFER request shall be regarded as received without an implicit request to grant the floor to the terminating MCPTT client.