topic Re: Music on Hold breaking down call on secure trunk in IP Telephony and Phones

Music on Hold breaking down call on secure trunk

tsmith054 — Sun, 17 Mar 2019 20:32:03 GMT

I'm trying to get secure trunks set up between our cluster and SBC. The trunk is up and calls are working. However, when I try to place a call on hold from the cucm side the call breaks down. I've identified the cause of this. During the re-invite, CUCM tries to send regular RTP back instead of SRTP for the MOH. According to the docs, if the remote device supports SRTP then CUCM should send SRTP for MOH. However, this is not what is happening. I've verified that this works from a secure cucm phone to another secure cucm phone. But this does not work from a secure cucm phone across a secure trunk. Any suggestions? I've restarted the IP Media Streaming service and that had no affect. I'll share a snippet of the SDP below where CUCM sends RTP instead of SRTP -

v=0

o=CiscoSystemsCCM-SIP 166772 3 IN IP4 <X.X.X.X>

s=SIP Call

c=IN IP4 <X.X.X.X>

t=0 0

m=audio 4000 RTP/AVP 0

a=X-cisco-media:umoh

a=ptime:20

a=rtpmap:0 PCMU/8000

a=sendonly

Re: Music on Hold breaking down call on secure trunk

Sreekanth Narayanan — Wed, 26 Sep 2018 16:18:30 GMT

Can you share the SDL trace for the sip trunk call being placed on Hold? It must have failed some condition in order to send regular RTP for MOH.

Re: Music on Hold breaking down call on secure trunk

tsmith054 — Wed, 26 Sep 2018 17:55:34 GMT

Attaching trace file for you. Thanks!

Re: Music on Hold breaking down call on secure trunk

Sreekanth Narayanan — Fri, 28 Sep 2018 06:18:03 GMT

Thanks for providing the trace. Is the MOH server "Device is Trusted" checkbox checked?
Also, do you have MTP required checked on the SIP trunk? Could you share the SDL and IPVMS trace for the same call?
I'd suggest raising a TAC case in parallel too.

Re: Music on Hold breaking down call on secure trunk

tsmith054 — Tue, 02 Oct 2018 13:24:05 GMT

Yes, the MOH server shows "Device is Trusted". I don't have MTP required checked on the trunk. If I check that, then the MTP offers RTP instead of SRTP to the far end. I currently have a TAC case open to see if this is a bug of some sort.

Re: Music on Hold breaking down call on secure trunk

Mark_B — Thu, 09 Jan 2020 09:48:13 GMT

Hi tsmith,

we have the same problem with disconnects. Did you found a solution which got an SRTP when a call is on hold?

Greetings
Markus

Re: Music on Hold breaking down call on secure trunk

Jose Gomez — Fri, 08 Jan 2021 20:11:17 GMT

Hi,

did yo get help from TAC?, could you share the fix for tihis?