[Asterisk-Users] Asterisk bandwidth tuning? (was DIAX)

[Roy Sigurd Karlsbakk]

> Dear Dan;
>
> Thanks alot for your kindly reply.
>
> Well, what u advise us to use if the bandwidth is about 22kbps (dial up
> connection in very old countries)?
>>
>> GSM Codec is 13k plus overhead. That may work?

No way. GSM is 13.2kbps, and with Asterisk's hardcoded 20ms 
packetization, this gives 29200bps with RTP-based protocols or 26000bps 
with IAX, and as long as Asterisk doesn't support silence suppression, 
this needs to be full duplex, and I doubt you don't get that from a 
modem. If we could add silence suppression, we could do with half 
duplex, effectively saving half the bandwidth. in addition, if we could 
increase the packetization to something like 50 or 100ms for extreme 
use (like dial-up), we could end up with a lot less. Say, using 100ms 
slicing with IAX and speex at 6.3kbps, we'll end up with effective 
bandwidth use of 8860bps plus ethernet. now that's something you can 
brag about....

roy