[Asterisk-Users] Re: Asterisk bandwidth tuning?

[Miguel Ruiz Velasco Sobrino]

I have an installation that connects in a [very] good day at 22kbps, but the normal is
about 18kbps.
I use de ILBC codec, and also change in iax.conf the
trunkfreq = 20
to 
trunkfreq = 30

It works, you can understand well the other person, but don't expect miracles or an
outstanding sound quality.


> 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

Miguel Ruiz Velasco


		
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