[SR-Users] rtpengine with rejected re-invites to new RTP ports

[Jeff Pyle]

Hello,

Given the following scenario with Kamailio and rtpengine in the middle:

- call establishes with G.711 RTP
- b-leg re-invites to T.38, indicating a different port number then he is
using for G.711
- a-leg refuses the re-invite with a 488
- call continues using G.711 on original port numbers as if re-invite
never happened

Will Kamailio and rtpengine handle it?

Today I have a functional configuration with rtpproxy on another SIP
proxy. It handles every scenario I have tried except this one. rtpproxy
sees the new ports in the re-invite and adjusts its session accordingly.
If the re-invite is rejected, the old media ports are no longer valid
through rtpproxy, and the call fails.

Is there an approach I can take with Kamailio and rtpengine to allow this
scenario to succeed?



Regards,
Jeff

[Richard Fuchs]

Post by Jeff Pyle
Hello,
- call establishes with G.711 RTP
- b-leg re-invites to T.38, indicating a different port number then he
is using for G.711
- a-leg refuses the re-invite with a 488
- call continues using G.711 on original port numbers as if re-invite
never happened
Will Kamailio and rtpengine handle it?
Today I have a functional configuration with rtpproxy on another SIP
proxy. It handles every scenario I have tried except this one.
rtpproxy sees the new ports in the re-invite and adjusts its session
accordingly. If the re-invite is rejected, the old media ports are no
longer valid through rtpproxy, and the call fails.
Is there an approach I can take with Kamailio and rtpengine to allow
this scenario to succeed?

This may or may not work with rtpengine. If it does work, it's simply a
lucky side effect, as this is entirely unsupported and I've never tested
it myself. Now if you had a final re-invite back to G.711, then that
would and should most definitely work.

cheers

[Jeff Pyle]

Richard,

After quite a bit of testing I can confirm there is no accidental success
here. With default settings the old RTP flow ceases 30 seconds after the
rejected re-invite.


- Jeff

Post by Richard Fuchs

Post by Jeff Pyle
Hello,
- call establishes with G.711 RTP
- b-leg re-invites to T.38, indicating a different port number then he
is using for G.711
- a-leg refuses the re-invite with a 488
- call continues using G.711 on original port numbers as if re-invite
never happened
Will Kamailio and rtpengine handle it?
Today I have a functional configuration with rtpproxy on another SIP
proxy. It handles every scenario I have tried except this one.
rtpproxy sees the new ports in the re-invite and adjusts its session
accordingly. If the re-invite is rejected, the old media ports are no
longer valid through rtpproxy, and the call fails.
Is there an approach I can take with Kamailio and rtpengine to allow
this scenario to succeed?

This may or may not work with rtpengine. If it does work, it's simply a
lucky side effect, as this is entirely unsupported and I've never tested
it myself. Now if you had a final re-invite back to G.711, then that
would and should most definitely work.
cheers
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