[asterisk-biz] Low Bandwidth VoIP

[Martin Vit]

>
> The short answer is no you can't get 32 *concurrent* channels on a
> 250kbps uplink
>
> With G729 as a codec you need around 32kbits per channel including the
> overheads from the voip protocol and tcp etc, so that would give you
> around 7 *concurrent* channels.
>

You are slightly wrong - G729 is 8kbit stream and the UDP overhead for 20ms
packetization is alltogether 25Kbit stream. In theory you can do 30
channels over 250 kbit with IAX2 trunking feature which puts all 30
channels to one big UDP packet which minimizes headers and UDP overhead.
There is also G729 variant using 6.4kbit stream.

There are also proprietary solutions (dont remember names) which do the
same like IAX2 does - multiplexing channels to big UDP packets.
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