Trunk SIP with Twilio : on Hold state doesn't work

[Sebastien Denoncin]

Hi guys,

I set a CUBE to create a trunk sip with Twilio.

* The incoming and outgoing calls work fine.

* call forward works

But I have a issue with the on hold state. 

When you put the call on hold from Cisco Phone, the music on hold is not played and when I resume the call the RTP doesn't work. It's the same behaviour when I need transfert the call and when I need initiate a conference.

I get the CCSIP message and I think that the On hold state is not Interpreted by Twilio.

Below the sip diagram. In yellow the on hold action.

In this diagram you can see that Twilio doesn't reply with SDP (RECONLY) and so the CUCM doesn't send with SENDONLY.

I have a workaround, I can set the voice-class sip midcall-signaling passthru media-change on the dial peer. but I think it not a solution in my case because with this command we have a limitation with SRTP-RTP

All guys who work with Twilio, have you an idea why it doesn't work without voice-class sip midcall-signaling passthru media-change command?

Thanks a lot for your input

Sebastien

[R0g22]

Who is the MOH source, CUCM or IOS GW ? There are two ways to implement MOH -
1. Set the "c" param in SDP to 0.0.0.0 or,
2. Use the sendonly/recvonly param

The latter is the newer and preferred mechanism but that does not mean that the former won't work.

So in your scenario, there should be a RE-INVITE to stop RTP and then there should be another RE-INVITE containing the IP address of the MOH source. Can you share the pcap here ?