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Avaya CS1000 7.5 with SIP trunks

Avaya CS1000 7.5 with SIP trunks

Avaya CS1000 7.5 with SIP trunks

We recently installed a new Avaya CS1000 7.5 with SIP trunks through s Sipera SBC.Calls seem to work fine and voice quality is good but we do have one big problem - calls to several audio conference bridges do not pass dtmf tones, or at least pass them in a format that the bridge can recognize. This happens on calls outgoing from the PBX to an external bridge and on some incoming calls to an internal bridge. Some calls from certain telcos and mobile providers work correctly while calls from other providers fail to send tones. This was not an issue on our old system with PRI service. Any ideas? Thanks.

RE: Avaya CS1000 7.5 with SIP trunks


to try and isolate this issue, you will need to run some traces at the SBC level. This should be done in parallel to traces by the carrier on the SIP side.

In the SBC, regardless of inbound or outbound, you should see certain SIP messages within the SDP. These messages will be identified with a value like fmtp:101 0-15.

This message denotes that a DTMF key has been pressed.

By tracing the SBC on outbound, you should see all calls generate these messages. This should essentially prove that the SBC and Session Manager / PBX are configured correctly.

You will also want to trace a good inbound and bad inbound call, and see where the issue lies.

As the SBC is communicating to a single carrier, you may find there are settings between the carriers that may be needed to allow the proper transmission of DTMF tones.

I think it is highly unlikely to be an SBC issue, more a carrier interconnect one.


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