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New Member

GSM.FR codec support with non-cisco Call agent

Dear all,

We use a Cisco AS5350 media gateway with E1 ports connected to the PSTN switch. We would like to use GSM.FR codec. Does AS5350 call support GSM.FR codec for MGCP controlled SIP calls ? Any one has tried that ?.




Re: GSM.FR codec support with non-cisco Call agent

yes, Cisco 5350 does support the GSM.FR codec. Be careful, though, because some third-party devices do not support the GSM.FR codec with all the payload types. In example, Asterisk IP PBX supports the GSM.FR codec with only one type of payload (32 I think).

New Member

Re: GSM.FR codec support with non-cisco Call agent


I just noticed in a cisco doc. describing the

"G.Clear, GSMFR, and G.726 Codecs and

Modem and Fax Passthrough" feature introduced in IOS version 12.2T. The document states GSMFR is supported for SIP and H.323, but not supported for MGCP (Table 1 in

Does it mean that it's not possible to make SIP calls through my AS5350 media gateway which is controlled by MGCP ? Any idea ?


Re: GSM.FR codec support with non-cisco Call agent

Not 100% sure, but I think that you can do it.

In my opinion, it matters what kind of protocol is used on the "voip" dial-peer.

if it says:

dial-peer voice voip

session-target sip-server


In such a case, you can use gsmfr.

But in the case below you can NOT:

dial-peer voice voip

application mgcpapp

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