As Phil described, its much more than 8 kbps, and the lower the frame rate,
the more bandwidth it takes due to the packet overhead. While turning up
our softswitch, we did a bunch of testing with different codecs at different
sample/frame rates on ethernet. Here are my *real world* results:
g711 (ulaw)
10ms frame ~= 126.5 kbps
20ms frame ~= 95.2 kbps
30ms frame ~= 84.7 kbps
40ms frame ~= 79.6 kbps
g729a (8 kbps)
10ms frame ~= 70.5 kbps
20ms frame ~= 39.2 kbps
30ms frame ~= 28.8 kbps
40ms frame ~= 23.5 kbps
We didn't test GSM.
So, most ADSL providers (including us) offer sync rates at speeds up to 800
kbps, however that speed is if the traffic is ATM (which it isn't), so by
the time you add IP/Ethernet overhead, the 800 kbps speed usually gives you
a payload somewhere around 670-690 kbps. So divide that by one of the
numbers above and round down and you will have your *theoretical* max
simultaneous calls assuming the connection is only used for VoIP. Now throw
in a few users and their email and web traffic and the number starts to go
down.
Hope this helps you out.
Regards,
Bill
----- Original Message -----
From: "Aloysius Thevarajah Lloyd" <[EMAIL PROTECTED]>
To: "TAUG" <asterisk@uc.org>
Sent: Monday, July 23, 2007 9:52 PM
Subject: [on-asterisk] VOIP Bandwidth - Calculation
Hi,
For a 10 SIP /g729 simultaneous use. What is the Best internet connection
recommended.
DSL or ADSL
What is the upload and download speed required? How to calculate the the
band width? ( g729a - 8 kbit/s 10 ms frames)
if u can guide me greatly appreciated.
Thank you
--
Lloyd
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