Path: utzoo!telecom-request Date: 23 Apr 91 17:29:58 GMT From: "Fred R. Goldstein" Newsgroups: comp.dcom.telecom Subject: Re: Caller*ID From US PBXs Message-ID: Organization: Digital Equipment Corp., Littleton MA USA Sender: Telecom@eecs.nwu.edu Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 301, Message 3 of 10 Lines: 54 In article , sbrack@isis.cs.du.edu (Steven S. Brack) writes... > (1) What will Caller*ID show as my number? > (2) What does E911 get as my number? > (3) What would an Ohio Bell trace show as my number? In general, if you are behind a PBX, then the public network knows only about the PBX trunk or group you're on. In some cases the trunk will return a hunt pilot, in others its own number, depending upon how it's set up. But none of the above three services can know your extension number, even though it can be dialed directly. Extension info is passed from the CO to PBX on incoming calls (DID service) only. On Centrex, it would show the number for your extension. Story behind the story: Back in the olden days (when steppers were used), the telco used to provide two kinds of Centrex. Centrex-CO used CO switches; that's what we have today. Centrex-CU put a switch (usually a Bell 701 stepper!) on customer premises and delivered a similar service. (Generally you paid about a quarter/month/phone less for -CU, essentially as compensation for the switchroom space.) Centrex-CU did deliver your extension number for billing purposes, 911, etc. (If they had 911 back then!) This was done via a data link from the switch to the CO, reporting which extension had seized which trunk. When the stepper went away, this service was made available to newer PBX users, under the name "Automatic Identified Outward Dialing" (AIOD). Many PBXs of the day, such as Dimension, supported it. BUT it was frightfully expensive, something like $3/month/extension. Since it didn't bill for WATS or FX, few customers found it useful. When 1983 came (when the FCC ordered all PBXs detariffed; this had noth ing to do with divestiture!), the last few remaining Centrex-CU systems were handed over to AT&T and repriced as PBXs. The previously-bundled trunks, including both DID and AIOD, went under telco tariffs. The total price went WAY up. I'm not sure if modern PBXs even support AIOD. The telcos priced it out of the market. ISDN, on the other hand, includes the capability, so it may make a comeback. (If they don't charge for it. They have no justification to charge, since it's built in to the protocol.) AIOD would make caller*ID behave in the expected fashion. Fred R. Goldstein Digital Equipment Corp., Littleton MA goldstein@delni.enet.dec.com voice: +1 508 952 3274 Do you think anyone else on the planet would share my opinions, let alone a multi-billion dollar corporation?