6.5 Handling of MIME bodies in a SIP message

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

The MCPTT client and the MCPTT server shall support several MIME bodies in SIP request and SIP responses.

When the MCPTT client or the MCPTT server sends a SIP message and the SIP message contains more than one MIME body, the MCPTT client or the MCPTT server:

1) shall, as specified in IETF RFC 2046 [21], include one Content-Type header field with the value set to multipart/mixed and with a boundary delimiter parameter set to any chosen value;

2) for each MIME body:

a) shall insert the boundary delimiter;

b) shall insert the Content-Type header field with the MIME type of the MIME body; and

c) shall insert the content of the MIME body;

3) shall insert a final boundary delimiter; and

4) if an SDP offer or an SDP answer is one of the MIME bodies, shall insert the application/sdp MIME body as the first MIME body.

NOTE: The reason for inserting the application/sdp MIME body as the first body is that if a functional entity in the underlying SIP core does not understand multiple MIME bodies, the functional entity will ignore all MIME bodies with the exception of the first MIME body. The order of multiple MCPTT application MIME bodies in a SIP message is irrelevant.

When the MCPTT client or the MCPTT server sends a SIP message and the SIP message contains only one MIME body, the MCPTT client or the MCPTT server:

1) shall include a Content-Type header field set to the MIME type of the MIME body; and

2) shall insert the content of the MIME body.