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Can MSS support G.729, iLBC, GSM audio codec, and so on?

Can MSS support G.729, iLBC, GSM audio codec, and so on?

We are often asked this question about audio codec. Some customers want to confirm whether MSS can work well with their SIP phones/clients who can support several audio codecs.

We often answer that it depends on their own SIP phones/clients. MSS, not matter local-MSS or cloud-MSS, doesn’t care audio codec by default.

Why we say that?

Please have a look at following figure which describe a basic media process model of MSS in a normal basic call.

From this figure, we can see:

(1) MSS only controls call signals.

(2) Media stream is processed by the clients themselves.

This model will reduce the work-load of the server since all media streams are bypass server, so it is unnecessary for the server to support several audio codecs.

But in some service scenarios, MSS need play audio to the SIP phones. For example, in auto-attendant or calling card services, MSS need prompt audio announcement and collect user input information. Obviously, MSS is required to support audio codecs in these scenarios.

That’s right. If MSS need process audio stream, it can support three kinds of audio codecs: G711a (PCMA), G711u (PCMU) and GSM.

By the way, after playing audio stream, the final media stream will be processed still in end-to-end model. Please refer to following media model of MSS for these scenarios:

Play audio stream


miniSipServer LTS upgrade to V2.10.6

miniSipServer LTS upgrade to V2.10.6

MSS LTS is upgraded to fix following problem or provide new feature:

(1) Fix a bug in GSM audo codec.

(2) Limit the max simultaneous call of FXO external line to only 1 by default since most FXO gateway can only support 1 call for one line.