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<big><font size="-1"><big><tt>Additionally Mark, a Channelized (also
called Integrated) T1 offers 24 channels for voice/data, but after bit
robbing (for signalling, etc) you only get around 56kbps per channel.
ISDN PRI over T1 has 23 b-channels of voice/data and one d-channel for
signalling, etc. PRI is preferred and most common. And of course, ISDN
PRI over E1 gets 30 channels of voice/data and 2 channels for
signalling.</tt></big></font></big><font size="-1"><font
face="Lucida Grande"><br>
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Jared Smith wrote:
<blockquote cite="mid:1207928055.3380.10.camel@hockey.jaredsmith.net"
type="cite">
<pre wrap="">On Fri, 2008-04-11 at 01:18 -0700, mark morreny wrote:
</pre>
<blockquote type="cite">
<pre wrap="">The T1 is 32 x 64Kbps channels ; Codec is GSM.
</pre>
</blockquote>
<pre wrap=""><!---->
That's incorrect... a T1 is 24 channels, and each channel is 64kbps.
There are also a few extra bits for framing, which adds up to 1.544
megabits per second in each direction. The audio comes across a T1 as
G.711 (not GSM as stated above), and on a T1 it's usually using ulaw
companding.
An E1 is 32 channels, and each channel is the same 64kbps. This adds up
to 2.048 megabits per second. Again, the audio is in G.711 format, but
alaw companding is typically used on an E1.
--
Jared Smith
Community Relations Manager
Digium, Inc.
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