Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request From: John Higdon Newsgroups: comp.dcom.telecom Subject: Re: Loop Start vs Ground Start, a User Intro Message-ID: <6388@accuvax.nwu.edu> Date: 14 Apr 90 07:04:19 GMT Sender: news@accuvax.nwu.edu Reply-To: John Higdon Organization: TELECOM Digest Lines: 48 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 10, Issue 254, Message 5 of 7 fmsystm!macy@cwjcc.ins.cwru.edu writes: > John, what you say should be true. Immediate ring is supposed to be a > feature on those new-fangled electronic CO's, but it doesn't seem to > work that way every time. > [...] > Another problem is intentionally slow ring sense in key systems and > PBX's. Ah, this is where you have me! While I experimentally determined that my CO (a 1ESS) hit the called line with ring voltage immediately 100% of the time, sometimes it was very short indeed, sometimes not even enough to be seen by my KX-T1232 (which is very quick). So if that first ring is missed, it would be several seconds before the next ring would come along and glare could easily occur. > So, ground start lives, and will be with us for quite a while yet. Just so there's no doubt, the two ITT3100s that I take care of have nothing but ground-start trunks (and design trunks at that). That is of course the real professional way to go. Naturally, glare is never a problem and the system has positive sense of when dial tone is actually seized. This makes things go much faster when the ARS works. But there is a sad truth. Ground-start is a USA phenomenon. As I'm sure our non-US readers will confirm, ground-start is not generally available worldwide. (I'm sure it's available in Canada.) It might be interesting to find out where, other than North America, a PBX user can hook up to ground-start circuits. > It should be noted that I find very few lines give loop disconnect > supervision anymore, except in older offices. The telco will > sometimes give you loop (CPC) disconnect on a loop start line, on > request, but don't count on it. Ground start is still the only > reliable way to prevent call collisions and get reliable disconnect. More and more, I am hearing that telcos are becoming sensitive to this. There are just too many devices out there that depend on loop current interruption for disconnect. Every switch used for CO service is capable of providing it, assuming that it is equipped with the proper line cards and the correct programming options are invoked. Repair service will listen to you now about that. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !