Codecs

chicha · #1 (**permalink**) March 5th, 2006, 06:05 AM

Which codec gives the best sound quality? Also, is the codec a function of (or determined by) the ATA or the service provider?

flydr2 · #2 (**permalink**) March 5th, 2006, 03:42 PM

The best quality is usually G711...

Your ATA can request any codec it support as the prefered codec... So if you set G711 as prefered #1, GSM as #2, G729 as #3

The your ata will try G711 1st, GSM 2nd, G729 3rd...

Then the connection is made with the 1st codec that your provider supports...

Lets say that your provider supports G711 and G729... Then your ATA will connect with G711
If your provider supports G723, GSM, G729... Your ata will Connect with GSM... If it fails for some reason it will try G729.

ctylor · #3 (**permalink**) March 5th, 2006, 07:16 PM

Unfortunately sometimes your provider supports G711 and G729 (and others) for instance, and you can set your device to prefer G711 and only fallback to G729 if for some reason that fails, but if your VOIP provider prefers G729 on its side, the conversation will run at G729 and not G711. My provider, INX (http://www.internationalnumber.com/index.html) which otherwise is a great service provider, performs that little annoying trick which makes me need to disable G729 entirely if I want to force it to run with my preferred G711 codec.

chicha · #4 (**permalink**) March 5th, 2006, 11:54 PM

Is there a website which lists the codecs preferred by individual VOIP service providers?

flydr2 · #5 (**permalink**) March 6th, 2006, 12:29 PM

No conplete list that I know about....

I find G729 works just fine. It's almost as good quality as a cell phone which uses GSM. The is really not much difference in the call quality.

I prefer G729 because if you happen to have a slow connection at any time the voice does not cut-out.

gremln007 · #6 (**permalink**) March 6th, 2006, 12:49 PM

Quote:

Originally Posted by flydr2

No conplete list that I know about....

I find G729 works just fine. It's almost as good quality as a cell phone which uses GSM. The is really not much difference in the call quality.

I prefer G729 because if you happen to have a slow connection at any time the voice does not cut-out.

How do you set the preferred codec(s) in Asterisk? I am having some quality issues and hope this will help.

Thanks!

Jonathan