Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!netsys!vector!telecom-gateway From: goldstein@delni.dec.com Newsgroups: comp.dcom.telecom Subject: Re: Audible Ringback vs. Ring Plant Message-ID: Date: 2 Aug 89 15:47:11 GMT Sender: news@vector.Dallas.TX.US Organization: Digital Equipment Corporation Lines: 39 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 270, message 8 of 11 In article , dupuy@cs.columbia.edu (Alexander Dupuy) writes... >In article John Boteler writes: > Office Tone Plant > ------ ---------- > Rolm PBX lucky to get anything! > >Actually, with Rolm PBX's anything means just that! We have one of these >monsters at Columbia now, and it has happened that someone calling me got a >busy signal which changed to a ringback after I hung up on the previous call! While I work for a company that's the largest competitor to Rolm's parent company (until the sale of Rolm to Siemens goes through...), I still don't like to see gratuitous Rolm-bashing. I spent quite a long time specializing in the care and feeding of Rolm switches (as a large customer) and while they certainly aren't perfect, they're generally predictable once you know the score. In the case above, Alexander Dupuy is reporting on "autopark", one of the nicest Rolm features that never caught on elsewhere! Autopark allows a caller to dial in to a DID extension and, if the line is busy, hear a PBX-generated busy signal. This is not supervised, so it's free. BUT if the caller knows about this feature, and listens to it long enough (the default is 10 seconds), then (if I remember) the busy signal is replaced by "music on hold" (still free) and the called party gets a call waiting tone. When the called party hangs up, the call rings through. Supervision occurs when it's answered. This is legal because PBXs are allowed to provide audible signaling to a DID caller without returning supervision; supervision is required only when a two-way path is opened. It should, however, be obvious that PBX manufacturers affiliated with long distance carriers (be they AT&T or Bell Canada) would not be particularly anxious to implement this feature! It's one of the widest loopholes in the supervision rules. Kudos to Rolm for taking advantage of it. (It's been around for over a decade.) Of course, not many end-users even know about it. Like many Rolm features, it's a bit hard to explain.