Changing Unity Codec from G.711 u-Law to G.711 A-Law

[r.heitmann]

Hi,

i need an a-law RTP-conversation (there are no problems to change the record-format and the wav-format of the stream-files!)

But Unity registers its lines ("ports") at startup with only 2 codecs at the callmanager - G.711 u-law and G.729.

It would be great, if Unity could register its lines like the cisco ip-phones with g.711 alaw, g.711 ulaw, g729, etc...

So, the callmanager doesn't allow a G.711 a-law RTP-Session with Unity.

Is this a problem with our TSP-Version? We use Unity 4.0(5) with TSP 8.0(1b).

Regards,

//Ronald

[mrmccann]

This isn't a problem with the TSP you have, it is by design. G711 u-law gives us the higher quality (but high bandwith) support, and G729a gives us the lower bandwith option for WAN links. We haven't had a strong need for Unity to support media streams in any other formats besides these.

[r.heitmann]

that's fine for enterprise networks.

But if you think a step further, to an worldwide SIP VoIP-Network, we need _all_ Standards.

uLaw is fine for the US. The Rest of the World uses aLaw and it is cheaper to buy another VoiceMail-System than implementing thousands of transcoding engines wich make an allmost stupid conversion from uLaw to A-Law.

But back to the point -

why can I convert all my Voice-Wav-FIles on my Unity-Server to G.711-A-Law, if this codec is not supported?

Why states the documentation G.711 (A-Law _and_ uLaw) is implemented by default?

Should this really be a design issue?

Regards,

//Ronald

[lindborg]

First, Unity does transcode to any codec you have installed on the box - it always has. So if you set the recording type to 7.11 aLaw (or GSM 6.10 or whatever) Unity will convert the inbound or outbound stream as necessary to match whatever CM negotiated when it connected to our ports.

As I understand it from the media guys, the TSP only supports negotiating G711 muLaw and G729a as the transport between Unity and the call manager. So other codecs that are used to store messages/greetings require we transcode into those codecs - the process is pretty light, it's not a big burden on the system. A lot of sites use GSM since it'll play on many hand held devices, for instnace. When those messages are played back out a call manager phone, we transcode them back into 711 or 729a depending on what's setup when the call connects.

[r.heitmann]

thank you for the answer :-)

As far I understand, it's a TSP-problem, since Unity supports all codecs!??

My current situation is, that i have to connect two voice-systems via SIP-trunk, one side callmanager the other is a service-provider voice-switch. (works great!). The sp-machine supports only A-Law, so we configured that on the SIP-trunk.

The callmanager seems to have no problem with A-Law so far, our phones can dial-out without any problem.

But it is not possible to call Unity from the outside, since the callmanager "knows" that unity only supports u-law and G729.

If Unity could support G.711, could it support it in the active RTP-Stream?

Regards,

//Ronald

[mrmccann]

Hello,

If you are still interested in getting this capability into Unity, I suggest you contact your local account team to get this on the radar for future Unity 4.x releases. There are some coding changes and testing required, so it will need to be committed as part of a future project.

Regards.

Mike