SIP trunk from CUCM to nortel tones and ringback issue, but works fine from CME

[Natalie Ramirez]

I have a Nortel phone system and we are evaluating CUCM.  

We setup a SIP trunk from the CUCM to the Nortel which is connected to a PRI, and I can dial local calls, but when I call my Cell phone, my cell rings, but all I hear is silence on my Cisco phone until I answer the cell, then it is a regular conversation.  However, when I call a POTS line, I get ring-back and everything works fine.  Call connects either way, with ring-back or without, it connects.  When I dial long distance, the Nortel system is supposed to present me with a tone to indicate that I need to enter my long distance dialing code, I never hear the tone.  I tried entering the code without hearing it, but that did nothing, eventually the call times out and I get a busy signal.

Cisco IP phone -- CUCM -- Nortel -- PRI -- PSTN

All of the above works with no issue with a CME.  Long distance tone comes across, get ring-back on all calls, no issues.

Cisco IP phone -- CME -- Nortel -- PRI -- PSTN

So to make everything equal, I added a router to the mix.

Cisco IP phone -- CME -- Cisco SIP router -- Nortel -- PRI -- PSTN

Cisco IP phone -- CUCM -- Cisco SIP router -- Nortel -- PRI -- PSTN

Still, CME everything works fine, I get ring-back on all calls and tone ready for long distance code.

I ran a debug for "debug voice ccapi inout" on the Cisco SIP router, I see the source/destination from CME and from CUCM all look correct.

I ran a debug for "debug ccsip messages" on the Cisco SIP router.  Messages are identical right up until the part of the debug on a successful call that says:

Jul 21 18:59:10.249: //-1/xxxxxxxxxxxx/SIP/Msg/ccsipDisplayMsg:
Sent:
SIP/2.0 180 Ringing

On the calls that do not get ring-back, this message never appears.  What is different about a CME sip trunk and how can I make a CUCM SIP trunk be the same as a CME SIP trunk?

on CME pointing to Cisco SIP router:

dial-peer voice 34 voip
 description Test1
 destination-pattern 9..........$
 voice-class codec 1
 session protocol sipv2
 session target ipv4:x.x.x.x
 dtmf-relay sip-notify
 no vad

How can I make the CUCM SIP trunk do everything just like the CME that works fine above?

On Cisco SIP router, pointing to Nortel:

dial-peer voice 24 voip
 description outbound test
 destination-pattern 9..........$
 voice-class codec 1
 session protocol sipv2
 session target ipv4:x.x.x.x
 dtmf-relay rtp-nte
 no vad

Cisco SIP router receiving calls from both CUCM and CME:

dial-peer voice 1 voip
 description incoming test
 voice-class codec 1
 session protocol sipv2
 incoming called-number .
 dtmf-relay sip-notify
 no vad

[Brian Meade]

Post the full "debug ccsip messages" output for a full call working and nonworking.

Might also be useful to grab CallManager traces.

[Natalie Ramirez]

Found the fix:

Device --> Device Settings --> SIP Profile

Then went line by line, changing each and every option, saving it, resetting it, then dialing long distance.

At the bottom, the checkbox that says:

Early Offer support for voice and video calls (insert MTP if needed)

I checked this, saved it, reset it, and dialed again.

I got the long distance dial code, called my Cell phone, and got ring-back.

I do not even know what that means, just know that it works. 

I had to create a copy of the "Standard SIP Profile" and assign it to my SIP trunk before testing.

Thanks for taking the time to look at my post. 

[Brian Meade · Accepted solution]

Sounds like the issue was setting up the early media.  You probably also could have fixed by changing the Rel1XX setting on the SIP Profile to Send PRACK if 18X contains SDP.  That may also save you some MTP resources.

[Natalie Ramirez]

Before I posted this discussion, I searched and found another post where someone recommended that.  I tried that first and it didn't work, but It was where I got the idea to just try every setting on that page one at a time.  So that solution technically led me to a solution that worked.