larry@uunet.uu.net (Larry Lippman) (05/23/91)
In article <telecom11.301.3@eecs.nwu.edu> goldstein@delni.enet.dec.com (Fred R. Goldstein) writes: > 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. > 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. AIOD first became available in 1966. There were two common versions of AIOD: the original "A1" version, and the smaller "A2" version. An AIOD implementation contained both apparatus in the CO and apparatus at the PBX site. The Western Electric AIOD apparatus utilized electronic circuitry that was unique and was largely based upon "magnetic core logic". Individual magnetic cores (i.e., not in a matrix like computer core memory) driven by transistors not only provided register storage, but were used to create AND, OR and other logic gates using multiple windings on a given core. Transistor relay drivers provided interfaces to switching apparatus. Ferrods were used as trunk scanning elements in the CO portion of the AIOD apparatus; the CO portion was much more complex than the PBX portion. The CO apparatus also used magnetostrictive delay lines as memory elements to build data frames for transmission to the CAMA interface. AIOD for the 701-series PABX also required the installation of ANI. The PABX ANI was similar to the older ANI B used with SxS CO's, but was a separate and distinct design for the 701. The smaller AIOD A2 apparatus was also available for the WECo 757A wire-spring relay/crossbar PABX. Believe it or not, there was Centrex-CU implemented on the 757 -- although very few installations were made. The 101 ESS was also used for Centrex-CU (sometimes referred to as Centrex-CE). The 101 ESS had internal capability for AIOD without requiring the hardware described above. AIOD was available for the 770 and 812 PABX's, but was short lived as soon as Dimension became available around 1975. The simple and much more practicable alternative to AIOD on the Dimension was SMDR. > 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 suspect that AIOD is long dead. When the Bell System began implementation of AMARC in the later 1970's, I believe that no AIOD interface (direct or through a BDT) existed, and AIOD quickly became an orphan. > I'm not sure if modern PBXs even support AIOD. I don't believe there was ever any non-WECo apparatus that provided an AIOD interface. The AIOD PBX --> CO data link was, um, also "unique". It used an FSK modem for serial data communication with mark and space frequencies of 1150 and 1850 Hz (it ain't even 202-compatible!). The transmission rate was 735.3 bits/sec - real common, huh? :-) Data was sent in 41-bit words (1 start bit, 20 bits to encode 4-digit trunk number, and 20 bits to encode 4-digit station number). Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 [note: ub=acsu.buffalo.edu] uunet!/ \aerion!larry
Dave Levenson <dave@westmark.westmark.com> (05/28/91)
In article <telecom11.391.1@eecs.nwu.edu>, kitty!larry@uunet.uu.net (Larry Lippman) writes: > I don't believe there was ever any non-WECo apparatus that provided > an AIOD interface. When I was in the interconnect business, selling Mitel SX-200 PBX equipment, I used to notice references to AIOD in the documentation for that product. We never used the feature, or equipped a customer's system to use it, so I have no first-hand experience with it, but the SX-200 PBX, apparently, was AIOD-capable. Anybody at Mitel care to comment on this? Dave Levenson Internet: dave@westmark.com Westmark, Inc. UUCP: {uunet | rutgers | att}!westmark!dave Warren, NJ, USA AT&T Mail: !westmark!dave Voice: 908 647 0900 Fax: 908 647 6857
Macy Hallock <macy@fmsys.uucp> (05/29/91)
> When I was in the interconnect business, selling Mitel SX-200 PBX > equipment, I used to notice references to AIOD in the documentation > for that product. The Mitel SX-200 and SX-100 and SX-2000 have AIOD capability. This is still available, but nobody uses it ... it's basically an obsolete protocol. It was included in the products because telcos wouldn't buy a PBX that could not support AIOD. It was used mainly for Centrex CU type services. I'm told there are some telcos with an AIOD tarriff still on the books. Not so here. Most of the modern CO's are the same way ... they can do AIOD due to telco specs, but never install or implement the feature. Macy M. Hallock, Jr. N8OBG 216-725-4764 Home macy@fmsystm.UUCP macy@NCoast.ORG Note: macy@ncoast.org is best reply path to me. uunet!aablue!fmsystm!macy [No disclaimer, but I have no real idea what I'm saying or why I'm telling you]