No ringback tone on incoming call via CUC call handler call flow

[layhlaing]

Hi everyone,

I am having no ringback tone issue on incoming calls via CUC call handler in the following environment.

CUCM: 8.6.2.22900-9

CUC: 8.6.2ES44.22900-44

Integration between CUCM and CUC: SIP

End-points: Cisco 9951 SIP, Cisco 7960 SCCP, Cisco 7942 SCCP

VG: Cisco 2921 with E1/PRI with PVDM3-128

Outbound Trunk: ISDN 30 channels

Trunk between VG and CUCM: SIP

Ringback tone is there if calls were made directly to DIDs.

The call handler call flow is as this:

-> 08 9333 7401 -> CFA - voicemail -> CUC CallHandler -> No greetings during BusinessHour, always transfer -> x7404 -> CFNA/CFB -> x7411 -> CFNA/CFB -> x7412 -> CFNA/CFB -> x7413 -> CFNA/CFB -> Mobile

Attached are VG config and debug output of 'debug voice ccapi inout', 'debug isdn q931' and screenshots from RTMT for the following test call:

Calling number: 0467784687

Called number: 0893337401

There was a ring, just once, "180 Ringing" message is there, as you can see in the screenshot 'Analyze Call Diagram*' but it has gone silent after that.

Both SIP trunks between CUCM and CUC have MRG (with active Annunciator) associated and they are  'MTP required' with 'MTP Preferred Originating Codec' of g729/g729a.

The SIP trunk between CUCM and site's VG also has MRG (with active Annunciator) associated and it is not 'MTP required'.

As you can see in the VG config, our codec preference 1 is g711ulaw.

Can someone please advise on how I should approach on this issue to be resolved? Thanks in advance.

Regards,

[Manish Prasad · Accepted solution]

Can you attach "debug ccsip message" from the VG.

[layhlaing]

Thanks very much for that. Please find attached output for debug ccsip message from the VG.

Regards,

[Manish Prasad]

Hi,

As per logs moh was played by 10.101.130.10 server on port number 4000 when ever phone is keep on ringing until it hits the CFNA timeout.

c=IN IP4 10.101.130.10
t=0 0
m=audio 4000 RTP/AVP 0
a=X-cisco-media:umoh
a=rtpmap:0 PCMU/8000
a=ptime:20
a=sendonly

So i would first check any blocking set on VG with that port number and IP address. Then i will packet capture VG inside interface towards CUCM to check whether the stream was reached at VG or not.

Please check these first and let me know.

[layhlaing]

Thanks again for that. 10.101.130.10 is the CUCM subscriber where end-points on that site register. There is no filtering between CUCM and VG but when I try to capture it using an access-list, I have no hits as yet.

I will check again in an another way to confirm. Thanks.

Regards,

[layhlaing]

Hi,

More checks have been done to confirm but I could not verify this. Have also done NMap scan but port 4000 was not in open list (both TCP and UDP). Have also check on VG using an access-list but there was no hit at all.

Music-on-hold is there though when the test call was put on hold.

Would you be able to explain why I am seeing '401 Unauthorized' in CUCM trace for the test call please? I should also mention that both of our CUCM and CUC servers are on dual-stack IPv4 and IPv6 but VG has only IPv4.

Thanks again.

Regards,

[Manish Prasad]

Can you please send debug ccsip message for an inbound call direct to an extension which is forwarded to other extension by CFB/CFNA , where caller hears ringback tone. Just wanted to compare those sip messages.

It may be picking up random port on different - different calls , so sticking to 4000 might not give you any result. What you need to check is the hit from 10.101.130.10 on inbound interface of VG through wireshark.

As far as 401 error is concerned we need complete sip message exchange to confirm why this error is generating , you need to set cucm trace to detail level with all the default selection.

[layhlaing]

Thanks for that. I have done a test call as advised - a direct call to an extension which redirect to other extension by CFB/CFNA. Please find attached output of debug ccsip message.

Even with this, I just become aware that the ringback seems to go silent (maybe  time out?) after about 5 rings in all five sessions as traced, as in RTMT screenshot.

Regards,

[Manish Prasad]

Can you enable early offer from sip profile applied to the trunk between VG and CUCM.

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

Again collect logs and send across.

[layhlaing]

Thanks very much again. I have enabled early offer in the SIP profile and the trunk has also been restarted.

Please find attached logs. It is a direct call to an extension as last time and the ringback tone went away after about 5 times for five sessions.

Regards,

[Manish Prasad]

Can you please collect CUCM traces of all the nodes for the call going through CUC . Do mention the time of the call.

Thank you.

[layhlaing]

Sorry for the delay. Please find attached traces for the last test call. The time of the call was Jun 20 21:14 WAST.

Thanks again.

[Manish Prasad]

It is a direct call to an extension as last time and the ringback tone went away after about 5 times for five sessions. - As 180 Ringing message sent by CUCM does not contain SDP parameters so its a responsibility of Telco to play ringback tone to the caller. I think you will not hear silence and the ringback will play as per timer set on each dn cfna if you call from an extension to 7404.

Now moving back to the main question , this trace is only for the direct call , i need cucm traces for the call which goes through the call handler . I want to look at the moh registered with 10.101.130.10 server and its function.

[layhlaing]

Thanks again for your assistance.  I have simulated a test call via a test call handler that just has been created.

Calling number: 0467784687
Called number: x7477 (Via Test Call Handler)
Time: 14:10 WAST

Please find attached CUCM trace. Early offer support in the SIP profile was disabled as it was giving some issues. Or should I create a specific SIP profile with early offer just for that site?

[Manish Prasad]

After looking at ccm traces i can tell you that moh was initiated and played by 10.101.130.10 on port number 4000.

14:10:47.488 |AnnDControl - RemoteIpAddr: 102730a (10.115.2.1) RemoteRtpPortNumber: 31050 msecPacketSize: 20 compressionType: 4|2,100,230,1.180158^10.115.2.1^*

14:10:47.488 |AnnDControl - star_StationOutputStationStartAnnouncement ConferenceID: 34735431, TCPPid = [2.100.13.709911] myIP: a82650a (10.101.130.10)|2,100,230,1.180158^10.115.2.1

You certainly need to scan your network's route path from 10.115.2.1 to 10.101.130.10 on port number 4000. Unless we ain't  sure that stream reached inside interface of VG , we cannot point it to the Telco.

Few more test you can do and let me know the behavior.

1. Add MOH server in the MRGL assigned to the SIP trunk.

2. Enable "MTP Required" on the sip trunk between CUCM and VG.

You can disable early offer.