[asterisk-users] G.711a or G.711u ???

[Matt Riddell]

On 24/03/10 8:41 AM, Alejandro Cabrera Obed wrote:
> Dear all, I have an Asterisk SIP server in a LAN environment and I want
> your opinion in order to decide the use of an audio codec:
>
> What audio codec is better, G.711a or G.711u ??? Which suites to my LAN
> voip calls ???

It basically comes down to where the system is being used and what 
codecs you're using upstream.

G.711a is aLaw and G.711u is uLaw.

uLaw is predominantly used in the USA.

aLaw is used in most of the rest of the world (although I think Japan 
might use uLaw).

If you're using an ISDN card then it will be talking aLaw or uLaw 
depending on where you are.

The idea is to avoid transcoding - i.e. converting between one format 
and another.

So, if you're using a VoIP provider instead of ISDN, it will depend on 
what they're using.  If your VoIP provider is outside of the US and 
accepts aLaw, then that's likely what you want to use (bear in mind that 
they might still use an upstream provider who uses G.729 etc).

Easiest option is to just choose aLaw or uLaw based on your country.

-- 
Cheers,

Matt Riddell
Managing Director
_______________________________________________

http://www.venturevoip.com/news.php (Daily Asterisk News)
http://www.venturevoip.com/exchange.php (Full ITSP Solution)
http://www.venturevoip.com/st.php (SmoothTorque Predictive Dialer)