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G.711 alaw and G.711 ulaw

CCM 3.3.2 C SP E

TSP 6.02 B

Unity 3.15 Unified w/ Exchange 2K

We implemented a Unity server in Germany and are having issues dialing in via the PSTN to Unity. Calls coming externally in via PSTN get a fast busy. When we change the codec on the router to be G.711 ulaw everything is happy.

I believe what should be done is changing the codec on the Unity box to handle G.711 alaw for the default. I am not sure how to do this????

Little help....

3 REPLIES
Gold

Re: G.711 alaw and G.711 ulaw

You can't change it in Unity. The Unity TSP can only support G.711ulaw and G.729a.

What you to do is use a voice class on the router to give G.711alaw precedence over G.711ulaw. That way all calls will do alaw but in the event alaw isn’t supported by an end point (Unity) it will negotiate to ulaw.

Keith

New Member

Re: G.711 alaw and G.711 ulaw

We tried this and it added a few seconds delay. Is this something just to live with or is there a better way.

Bob

Gold

Re: G.711 alaw and G.711 ulaw

There shouldn't be a delay but I would need a debug ccapi in out to see where the delay it.

A better solution is to switch to ulaw. On the IP side it doesn't make a difference if you use ulaw or alaw. It's the telco side that needs alaw.

Keith

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