Moved 180 Ringing response from core to app (menu module)

[juha-h]

Required by https://github.com/baresip/baresip/pull/3088

[juha-h]

Christian Spielberger writes:

In my opinion sipsess_accept() should send a reply. @alfredh and @sreimers please review and decide!

If so, we can sent 100 Trying like it was.

Should we revert this, when we have another solution?

It is OK to me to revert this IF the other solution fixes the bug, i.e., does not by default send 180 Ringing response.

[maximilianfridrich]

The 100 Trying response was not accepted before. See response of Alfred:

please read the spec carefully regarding 100 usage and 101-199 replies: https://datatracker.ietf.org/doc/html/rfc3261#section-21.1.1 100 Trying should only be sent by a SIP Proxy...

https://github.com/baresip/re/pull/808#issuecomment-1550970325

[juha-h]

Maximilian Fridrich writes:

The 100 Trying response was not accepted before. See response of Alfred:

please read the spec carefully regarding 100 usage and 101-199 replies: https://datatracker.ietf.org/doc/html/rfc3261#section-21.1.1 100 Trying should only be sent by a SIP Proxy...

https://github.com/baresip/re/pull/808#issuecomment-1550970325

RFC text uses term "next hop server" that very well can be an UAS = User Agent Server. See for example this Cisco example call flow:

https://community.cisco.com/t5/collaboration-knowledge-base/basic-sip-call-flows-amp-troubleshooting-commands/ta-p/3110162

But this PR does not currently send a 100 Trying response.

Please commit this PR or provide another one that does not by default send 180 Ringing response to INVITE request.

[cspiel1]

@juha-h Can we close this?

[juha-h]

Yes, forgot about the re PR when I closed the baresip PR.