[Asterisk-Users] Beyond T1

[Marcelo Pacheco]

I'm no E1 expert, but as I understand one channel is wasted with framing, so 
it is as 2048000 bps link, where one 64000 bps channel is wasted with 
signalling. So there's 31 channels left. If you use E&M, FXS or FXO, you 
could get 31 voice channels, with PRI or MFC/R2D you get 30 voice channels.

I now that from the fact that a full E1 with EuroISDN gives you 30 voice 
channels.

An a full E1 with Brazilian R2D also gives you 30 voice channels, as one 
channel is used for signalling as CAS (Channel Associated Channeling), where 
each 4 bits is used for each channel.

The only situation where you get closer to actual 2mbps out of an E1 channel 
is when you run SyncPPP, Frame Relay or another bit synchronous protocol on 
the full trunk/link, where you throw away the channelling and use the whole 
link as one big synchronous bit pipe.

Marcelo Pacheco

Em Qui 16 Set 2004 13:26, Andrew Kohlsmith escreveu:
> On Thursday 16 September 2004 12:17, Andrew Thompson wrote:
> > Depending on where you using the circuits, you might try an E1. It uses
> > the same total bandwidth as a T1(I think), but splits the channels at
> > 56K instead of 64K, yielding more channels. (And now I can't remember
> > the number.)
>
> uh, no.  This is definitely NOT correct.
>
> T1 is 24 8-bit channels + 1 framing bit sent 8000 times a second.  24*8+1 =
> 193 bits per frame * 8000 = 1554000bps.
>
> E1 is 32 8-bit channels + 1 framing bit sent 8000 times a second.  32*8+1 =
> 2056000bps.
>
> (my E1 knowlege is poor, I hope I am not furthering the misinformation
> here)
>
> In both cases you get 64kbit clean channels unless you're doing robbed-bit
> (inband) signalling.
>
> -A.