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No ringback on PSTN


We have a problem where no ringback is generated to the PSTN when our SIP outbound provider sends a "183 session progress". Another SIP carrier we use sends "180 ringing" and ringback is generated.

The problem manifests itself when an IP phone is set to call forward to a mobile.

Call flow would be as follows;

PSTN--->H323 gateway---> CCM --->SIP

We are using CCM 6.1.3, the H.323 gateway is a 5300 running 12.3.15a, SIP is our outbound provider

We have tried settings outlined in below links but to no avail

Has anyone experienced a similar issue? Any help appreciated


Re: No ringback on PSTN

You may be running into bug CSCsq67485. The bug states that it is fixed in 6.1.3, but TAC has confirmed that it is not actually fixed until 7.0

CSCsq67485 Bug Details

No ringback tone for SNR calls incoming through the H323 gateway


Callers get no ringtone or one ring and silence


Incoming calls are through H323 gateway; called number is enabled for mobility and call is routed to Remote Destination


In addition to the fix for this defect, please make sure to set the service parameter "Send Progress Timer" to 1 sec more than DelayBeforeRinging Timer

If H323 ICT is used, this "Send progress Timer" should be adjusted to 1 sec more than DelayBeforeRinging Timer in clusters in the call path

This workaround is addressed in CSCsq92647



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