Date: 04 Sep 1998 11:13:48 +0200 From: Martin Recktenwald <mreckt@wurzelausix.CS.Uni-SB.DE> To: freebsd-isdn@FreeBSD.ORG Subject: Re: called-back, rejects and auto hangup Message-ID: <wtzyas01bqr.fsf@wurzelausix.cs.uni-sb.de> In-Reply-To: hm@hcs.de's message of "Fri, 4 Sep 1998 09:50:25 %2B0200 (METDST)" References: <m0zEqdV-0000dyC@hcswork.hcs.de>
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hm@hcs.de (Hellmuth Michaelis) writes: > >From the keyboard of Leo Weppelman: > > > the call-reference/TEI combination is unique, _only_ the > > combination, right? > > The TEI is the "address" of a device on the S0 bus and uniqely identifies > a device. Or even, it is the address of a unique instance in a physical > device - a physical device may have more than one TEI assigned to it. > > A TEI is a layer 2 concept. > > The Call Reference uniqely identifies a single call control transaction > on a given S0 bus. Really? To quote Q.931: "Call reference values are assigned by the originating side of the interface for a call. These values are unique to the originating side only within a particular D-channel layer two logical link connection." A "layer two logical link connection" is identified by a TEI. If I understand this correctly, it means that a call reference without a TEI is meaningless. There could be the _same_ call reference for two different TEI values. This doesn't matter for normal TE's like a phone because they don't use more than one TEI anyway. Martin. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message
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