SIP Trunk from ISP DTMF issue (CUCM and CUE)

Answered Question

Hi all,

Currently I'm running a acceptance test on a SIP Trunk from our ISP. Everything is working fine except the DTMF.


Setup:

[GenBand SBC] ---- [SIP Trunk into CUCM 7.1] ---- [Cisco Unity Express 7.0]


The SIP Trunk as well as the CUE are in the same region supporting only G.711. On the SIP Trunk I've tried all different kind of DTMF configurations (No Preference, RFC 2833 and OOB). We've tried to force the GenBand SBC to only use RFC 2833 as well as the SIP Trunk. But this didn't work, not even after we added a MRGL with MTP's.


Is there some sort of best practive to implement DTMF over a SIP Trunk? Is there a way I can do some debugging on the CUCM/CUE?


Kind regards,


Paul van den IJssel

Digacom

Correct Answer by Zhiping Cai about 6 years 10 months ago

Hi,


Can you try to check "Accept Unsolicited Notification" of the SIP Trunk Profile which your SIP trunk is using?

Go to System -> Security profile ->  SIP Trunk Security  Profile -> find the profile name in use (Default: Non Secure SIP Trunk Profile).


Now CUCM should not respond with 403 Forbidden.


Hope that helps.

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j.hazenberg Thu, 07/15/2010 - 01:34
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Hi all,


Here is some aditional information from the ISP side. We are using a Genband MSX release 4.3m6 and we have the following options for DTMF transmission:


SIP NOTIFY

SIP INFO

RFC2833 (payload type 101)


When we send DTMF to the CCM with SIP NOTIFY we see a 403 Forbidden comming back from the CCM.


One other thing i noticed is that when we place a inbound call to the CCM --> IVR (using RFC2833) the 200OK doesen't contain a media type 101 (rfc2833), and if i'm correct the CCM was configured for RFC2833 at that point. If the SBC doesen't receive the correct media type in the 200OK it assumes that there is no support for RFC2833 and it will fallback to inband DTMF tones in the audio stream.


Could this have something to do with the DTMF transmission between the CCM and unity express? Is the DTMF transmitted in the siggnaling between the CCM and the unity express? Or is it using RTP payload like RFC2833 does?


Here also a brief description of our setup:



[ISDN30/DMS100]--------------------[Cisco AS5850]------------------[SIP proxy]--------------------[Genband SBC]-----------------[CCM]

                               ISDN30                                 SIP                            SIP                                       SIP



Please find attached a pcap trace of the DTMF/NOTIFY test.


Thanks in advance,


Jan Hazenberg

Correct Answer
Zhiping Cai Thu, 07/15/2010 - 06:11
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  • Cisco Employee,

Hi,


Can you try to check "Accept Unsolicited Notification" of the SIP Trunk Profile which your SIP trunk is using?

Go to System -> Security profile ->  SIP Trunk Security  Profile -> find the profile name in use (Default: Non Secure SIP Trunk Profile).


Now CUCM should not respond with 403 Forbidden.


Hope that helps.

Now here's the next challange.. SIP Trunk is in a region running G.711. IP Phone A and B are using G.711, IP Phone C and D are using G.729. All devices have a MRGL containing both MTP (G.711) and CFB (G.711). Setting up a conf call to the G.711 phones is working fine. But when I try to setup a conf call to phone A and B, or A and C. The G.729 call gets terminated. It should use the CFB and MTP just as it whould with a normal H.323 or MGCP gateway connected, right?


Sorry, nevermind my previous posting. I need hardware transcoder to get this to work..


Kind regards,


Paul van den IJssel

Digacom

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