SIP-based CIPC & Unity 5.0: no DTMF apprehension

Unanswered Question
Jun 9th, 2008

Hi, all,

Have CIPC 2.1(3) while connecting to Unity 5.0(1): Unity doesn't apprehend DTMF user input at all.

Then I got CIPC traffic dump and saw DTMF are generated both RTP-2833 and SIP NOTIFY messages.

Unity answeres "I have not hear your input ..." or something.

No problem occurs when convert CIPC to SCCP code.

If dump or anything is needed let me know, I'll attach.

Thank you.

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gpulos Tue, 06/10/2008 - 05:29

what codec does your phone talk?

if g729, you may have distorted dtmf tones that unity is not understanding.

any voip gateways between the cipc and unity? if so, you'll need to verify the dtmf-relay on the gateway and/or dialpeers.

rtp2833 and sip notify are 'in-band' dtmf-relay options which if the RTP stream is compressed, may cause distortion of the tones.

are these calls to/from the pstn to/from unity?

verify the codec(s) used in the communication between cipc and unity as well as try an 'out-of-band' dtmf-relay if possible such as 'h.245-alphanumeric'

if still a problem, post all codec(s) in use and any voip gateway ios configuration so we can further assist.

eschulz Tue, 06/10/2008 - 07:19

RFC2833 may be in the RTP stream but it shouldn't be impacted by the codec. The RFC2833 digit events will show up as a separate payloadtype from the audio packets.

I assume Unity is connected to CCM via SCCP? If so, you should verify what digit method is negotiated in the call setup to Unity. If CCM tells Unity to expect a non-zero RFC2833 payloadtype, then you should verify (via network capture?) that the RFC2833 events are reaching Unity. If CCM tells Unity to expect a 0 RFC2833 payloadtype then Unity will expect to see out-of-band digits in the SCCP signaling. In this case, CCM should be translating the out-of-band NOTIFY digits into SCCP digits events for Unity.

If on the other hand Unity is connected to CCM using SIP, then I think the next step is simply to confirm that the digits are reaching Unity. Again, a network capture at Unity is a good way to see this.


Tobivan_Helden_2 Tue, 06/17/2008 - 04:06

Hi, all,

1. There is no voice gw between IP Phone and Unity. The site is the same (IP Phone CUCM Unity).

2. I've also tried to test 7941G IP phone with SIP firmware SIP41.8-3-5S. Result is the same as with CIPC.

3. I got a captured file from CUCM while IP Phone was calling to Unity.

It contains SIP over TCP with NOTIFY messages (out-of-band).

These messages contain the digits (I pressed on the phone while I'm hearing Unity greeting) in their bodies.

4. Unity is integrated with CUCM via SCCP (CM TSP 8.2.1).

How/where can I force CUCM to make a SIP Notify DTMFs (out-of-band) to SCCP DTMF (out-of-band) translation ?

This is more preferable for me, than RTP2833 to SCCP.

eschulz Tue, 06/17/2008 - 08:17

In your capture from CUCM, you can look for a StationOpenReceiveChannel SCCP message sent to Unity. That message should contain a RFC2833PayloadType parameter. If this parameter is set to zero, then Unity will expect to see the digits in SCCP signaling. Sorry, I don't have any suggestions on how to ensure CUCM does the translation. If RFC2833PayloadType is greater than 0, then Unity will only expect to see RFC2833 digits in the audio stream. These digits likely won't show up in the CUCM capture because the audio stream is typically direct between the phone and Unity.



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