Date: Sat, 9 Dec 1995 10:29:45 +0100 (MET) From: grog@lemis.de (Greg Lehey) To: chuckr@glue.umd.edu (Chuck Robey) Subject: Re: Who's working on ISDN? Message-ID: <199512090930.KAA00331@allegro.lemis.de> In-Reply-To: <Pine.SUN.3.91.951207232009.25836A-100000@mocha.eng.umd.edu> from "Chuck Robey" at Dec 7, 95 11:23:47 pm
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Chuck Robey writes: > > I used to be a voice/digital telecomm guy, before I went back to school, > and I'm really curious. I know the European digital pipes are 2.048 MBS, > while ours are 1.544 MBS. I saw above where it said NT1. Are the NT1 > rates the same here/there, or does the card do both 2.048/1.544? The boards we're talking about here are Basic Rate boards, still usually known as S0 in Geramny. The standard is the same everywhere: 2 B channels with 64 kb/s (which can be used for voice or data), one D (signalling) channel with 16 kb/s. Also, for the signalling guys, there's another 48 kb/s channel timing. The NT1 (known in Germany as NTBA) is an active electrical interface to the externatl telephone line. Basic Rate in the US has a problem that the trunks usually run 64 kb/s with inband signalling. As a result, they take one bit per byte of the B channels, and you end up with 56 kb/s B channels. I don't think that German ISDN boards can handle that, though maybe it's a software option. Greg
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