It's in the ANSI spec for North American ISDN. I'd guess that AT&T does,
since it's essentially just a copy of the Bellcore specs. Our ISDN stuff
doesn't. I've never seen an ISDN line intentionally provisioned over AMI,
though I have it on good authority that it is done sometimes.
> >(And, of course, it should be noted that T1 lines are full-duplex.
> Always.)
>
> One nit here - T1's are actually two way simplex, not full duplex.
> Data only travels in one direction, and there are 2 paths to create
> "full duplex".
>From a user's point of view, they are full duplex. Full duplex means that
you have a separate transmit path and a separate receive path. You can't
buy just a T1 receive-only or a T1 transmit-only pair, nor could you use
such a thing if you did (since FDL wouldn't work right), so it's not quite
the same as two completely separate simplex links.
The point is that there are folks out there who think that a T1 is a *total*
of 1.536Mbps user data (well, some think it's 1.544, but that's another
story entirely). It's not. It's 1.536Mbps each direction. All the time.
--- James Carlson <carlson@xylogics.com>, Prin Engr Tel: +1 508 916 4351 Bay Networks - Annex I/F Develop. / 8 Federal ST +1 800 225 3317 Mail Stop BL08-05 / Billerica MA 01821-3548 Fax: +1 508 916 4789