[Asterisk-Users] ZtDummy vs Hardware

[Andrew Kohlsmith]

On December 28, 2004 11:44 am, Rich Adamson wrote:
> I would seriously doubt that you can actually squeeze 12 channels through
> that dsl and obtain anything reasonable for quality, regardless of which
> asterisk codec you choose. But, it certainly would not be that hard to
> test it and validate assumptions.

3.4kB/sec per GSM codec (real live wire speed, including all overhead)
12*3.5 (add some margin): 42kB/sec

80kbps * 12 is 960kbps -- you could almost fit 12 ulaw conversations into my 
ADSL pipe.

My DSL line has an 800kbps upstream so this would easily fit, especially if 
you have IAX2 trunking turned on (and assuming the conversations are going ot 
the same endpoint).

> If that dsl is used for anything else (including hackers/scanners hitting
> the IP associated with the circuit), quality will vary. Don't forget to
> add the IP packet overhead to the codec bandwidth estimates.

This is true regardless of your internet connection, DSL isn't any different.

-A.