SIP endpoint 3911 on UC520 cannot send DTMF to outside call

Unanswered Question
Sep 23rd, 2008

Dear all,

I have configured UC520 to support SIP IP Phone 3911.

Everything works fine, except when user make an outbound call to PSTN which is happen to be an IVR that need to input a digit. Here it seemed that SIP Phone could put the DTMF digit.

Is there any specific commend I need to put in?

I have this problem too.
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slongewa Tue, 09/23/2008 - 07:19

You would want a "dtmf-relay sip-notify" on your dial-peer for the outbound PSTN calls.

Hope this helps,


jaruneesup Sun, 09/28/2008 - 05:58

Hi Steve,

Please give me a command example of this outbound PSTN calls.

As I try to put the command in the dial-peer pots but it doesn't recognize the command.

Thank in advance.

Marwan ALshawi Sun, 09/28/2008 - 06:18

dial-peer voice 6800 voip

destination-pattern 5...

session protocol sipv2

session target ipv4:

dtmf-relay sip-notify

codec g711ulaw

no vad

The equivalent method in the SIP domain is to use a SIP NOTIFY event. However, this is not well standardized. The original SIP DTMF NOTIFY implemented in the Cisco IOS Voice Gateway software is based on an early draft proposal for this mechanism and, therefore, is not supported on most third-party SIP products. However, this mechanism is adequate provided that you are using only Cisco IOS voice endpoints with Cisco IOS Release 12.3(4)T or later. You also need to transport DTMF keypad events across VoIP to an IOS PSTN voice gateway for regeneration as an audio signal into a PSTN trunk or FXS port.

To enable the SIP NOTIFY for dtmf-relay, add the following command to your SIP VoIP dial peers:

dtmf-relay sip-notify

if helpful Rate

jaruneesup Thu, 10/23/2008 - 18:34


I had already put in the command SIP VoIP dial peers exactly as your post, but that still isn't work as well.

Please help!!!


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