telecom@eecs.nwu.edu (TELECOM Moderator) (03/18/91)
Several days ago, an inquiry was made here about Front Door to Apartment phone service, sometimes known as Enterphone or Interphone Service. A message appeared in the Digest some time ago about this, and I will try to recap that earlier message for those who missed it. Prior to divestiture, Illinois Bell (and perhaps other telcos) offered a type of hybrid central office service which allowed for calls between the front (or security) door in an apartment building lobby and the individual apartments, using a three digit code. The call would ring in on the actual phone line in the specified apartment. The service was called 'Enterphone', and involved dedicated pairs between the apartment building and the telco central office. A person in the lobby would use the phone -- typically a well secured wall phone with an armored cable to the handset -- to dial a three digit code for the tenant desired. These codes were listed in a directory by the phone, and did not give actual apartment numbers or phone numbers, but merely the three digit code. The central office would get this information, and translate it to a specific wire pair going to the apartment. They did NOT translate it to a phone number and then redial that phone. By translating to the wire pair, the idea was the door code would always work with the specified apartment, regardless of the phone number actually in service there. When a visitor dialed the desired three digit code, the central office would go on the associated pair and test for busy. If not busy, it would seize the pair, and send a special ring (a very short double ring of the format ding! ding! ... ding! ding!). This told the apartment tenant that the call was coming from the front door rather than elsewhere, giving them the opportunity to avoid answering if desired. If the pair was busy, then the central office sent a call waiting tone instead. The tenant would answer the phone (or flash, if on a call), and be connected with the door. If on a call, then the central office call would be put on hold while the tenant was connected to the door. All calls from the door had a one minute (combined ringing and talking) time out. The idea was, this was intended as a front door intercom; not an actual phone line. After identifying the party at the door, the tenant could dial '4' to unlatch the door for a pre-detirmined period of time -- usually five or ten seconds. Or, they could simply hang up and refuse entry to the person in the lobby. If they were on a call waiting, dialing '6' would deny entrance, disconnect the door call and return them to the call on hold. If a central office call came in while the tenant was talking to someone at the front door, then that call also sent a call waiting signal. One special 'control' pair from the central office was used to send a small amount of current to a relay in the apartment building which in turn controlled the electric door striker. The amount of time it would hold open was set in the central office by pre-arrangement with the management of the building. Usually there were a few extra administrative extensions tied into the Enterphone system, such as a phone for the on-premises management office or caretaker. When tenants were out (or the management office closed) then calls via Enterphone could be picked up by an answering machine if the tenant otherwise had one on the line. Calls could NOT however be forwarded elsewhere. Even if the tenant had their phone call forwarded to some other location, the Enterphone would 'ring through', since it was not really dialing the phone number, but simply grabbing the specified pair temporarily. One disadvantage to this system was that the pairs coming to the building had to be expressly dedicated to that building ... no pair swapping on the poles to meet the needs of the neighborhood otherwise, since this would cause the front door line for the apartment in particular to go out unless a corresponding change was made in the central office, which was rarely the case. In the central office itself, there were jumpers between the Enterphone device and the frames, and these had to be tagged with warnings not to swap them out, etc. Another disadvantage was that if something went wrong en-route to the building; i.e. a cable out due to fire or flood, etc, then this caused the apartment building front door to go out of service as far as intercom service / electronic opening was concerned, although of course it could still be opened with a key. In the normal course of business, the Enterphone system usually carried a guarenteed two hour repair turn-around, 24 hours per day, seven days per week. Obviously it was a critical application. If an apartment was vacant or occupied but without regular phone service (tenant on a credit disconnect, etc) then the phone in the apartment would still work for Enterphone purposes only. Usually the caretaker of the building had two or three plain black rotary dial phones which belonged to telco that he was allowed to give new tenants on a temporary basis until they got their own phone installed. This allowed them to use the front door intercom from the time they first moved in, even if their own phone was not installed for a couple days. And as noted above, it did not matter what the tenant did with their own phone, or whether they had an unlisted number, changed their number, etc. Enterphone was independent of the actual service in the apartment. The cost of the service was billed to the apartment building, and the rates (as of about 1980, prior to divestiture) were as follows: $1.10 per month per apartment. $5.00 per month for the phone from the lobby to the CO. $5.00 per month for the circuit from the CO to the door-opening relay. $50.00 per month for the common equipment in the CO. The lobby phone was touch-tone if desired for an extra dollar or so per month. It could likewise be a speaker phone mounted in the wall without an actual receiver attached (the first button pushed on the touch tone pad would open the circuit -- usually those models used a dummy digit such as '1' as first-digit-filler for that purpose) for a couple dollars extra per month. An 'extension' of the lobby phone could make a line appearance on a (for example) six-button, five-line phone in the manager's office, allowing the manager to call any individual apartment via the Enterphone for a couple dollars extra per month. So, a fifty unit apartment building would pay about $115 - $120 per month for the service. It was a very reliable service, and offered great security to tenants, since a visitor who did not know what apartment was desired had to ask the person on the phone while they were at the door. The tenant was free to answer or not, and admit them or not. The special ring tipped off the tenant as to the nature of the call. Then came divestiture, and in His Wisdom, the Judge ruled that Enterphone was just the sort of service telcos should NOT be allowed to offer. Was Enterphone to be considered Customer Premises Equipment, or Central Office / Centrex equipment? Well, the decision was telcos could no longer offer it, but to avoid a great deal of inconvenience to existing customers, they were permitted to 'grandfather' the service and continue making it available only to existing customers for (I think) another ten years. About the time of divestiture, the same service became available as purely CPE, or Customer Premises Equiment. All that really happened was the 'common-equipment' which had previously been located in the central office, renting for $50 per month started showing up in the basement of apartment buildings, where it was typically mounted in or near the main terminal box for the building. Instead of being rented, it was offered for sale, at somewhere around $2000. Pairs coming into the building are tied down on one side of the common equipment -- which also had been given a new name -- <I>nterphone -- with an 'I' instead of an 'E' in the process. The house pairs go out the other side of the unit and off to the apartments as always. Under this arrangement, although keeping the house pairs properly lined up remains critical to the functioning of the Interphone, telco is free to do as they wish with pairs to <-> from the central office, as long as they tie them down correctly on 'their side' of the Interphone, of course. The service functions the same as the old Enterphone, with distinctive ringing, call waiting and three digit codes from the door to each apartment. Of course there is no longer a charge for each apartment line. Nor is there a charge for the lobby phone or the circuit and relay to open the front door, since these things now belong to the apartment building itself. When it breaks down, you get it fixed wherever you like, at your convenience :) ... but the companies which sell Interphone (it is manufactured by GTE of Canada) will also sell you a maintainence contract with prompt repair service. Of the two units I am familiar with, one was Enterphone; the other was Interphone. They were virtually identical, except the Interphone unit has a speakerphone in the lobby with sturdy metal touchtone buttons built into the same metal panel in the wall ... nothing there for vandals to tamper with. In that 96-unit apartment building, the digit '1' activated the speakerphone, and the two digits following called the apartments and caretaker's office. The common equipment was about the size of an Apple computer, operated on a 110 volt AC power supply, weighed about ten pounds and hung on the wall next to telco's inside terminal box in the basement. Various CPE suppliers sell/service Interphone. You can inquire at any large telecommunications equipment company. I can't honestly say what the price would be now-days. This sort of system is much superior to the arrangement where you dial a code (or punch a speed-dial button) on a phone and have it translated into a seven-digit number it dials on a regular phone line. The reason is, those systems are useless if the apartment phone is busy (and does not have call waiting) or if there is no working line in the apartment. Likewise, if the person is gone and has call forwarding, they probably do not want a visitor at the front door to have their call forwarded to wherever. Finally, the apartment complex has to pay for calls over a regular line using speed dialing techniques, and there is the risk someone will place unauthorized calls over the front door phone as well unless it is controlled carefully. Admittedly, the speed dial / abbreviated dialing to a seven-digit number scheme is a less expensive way to go if you want front door to apartment intercom service over regular phone lines. But a system like Interphone, while more expensive to install, costs less in the long run with no phone charges, no risk of unauthorized long distance calls, and no concern about the apartment phone being busy or out of service. And quite obviuously, the caretaker does not have to reprogram Interphone every time a new tenant moves in or an existing tenant changes their phone number, as is the case with the units which merely outdial on a regular phone line using speed dial codes. I hope this gives the original writer a few ideas to work with. Patrick Townson
king@uunet.uu.net (Steven King) (03/21/91)
Pat, you forgot to mention the downside of the {E,I}nterphone.
(Warning: Anecdote Alert!)
A friend of mine had been sent overseas on business for a month or so.
After he got back I was going to stop over to say "hi" to him one
Saturday morning. I got there, and buzzed his apartment. Well,
unbeknownst to me at the time the intercom was an Interphone
arrangement, the type that doesn't interrupt calls in progress. He
had a data call up you see, catching up on a month's worth of email
and news ... all I got was a busy tone! Luckily his second-floor
apartment had a window that was literally a stone's throw from the
ground.
The call-interruption flavor wouldn't have helped much either. Call
waiting would have kicked in and knocked him off the modem (assuming
that it can't be cancelled with *70 or something, in which case he
would have cancelled it). The modem would have put the line back
on-hook. Would the phone ring in such a situation? If so, no
problem. Otherwise my friend would have cursed the demon-spawn named
Line Noise and simply redialed before I could try again!
No, give me an honest-to-god dedicated intercom any day. Better yet,
give me a dwelling place free of these !#$%^# modern "conveniences"!
Steven King, Motorola Cellular (...uunet!motcid!king)
[Moderator's Note: By definition, I/Enterphone WILL interrupt a call
in progress. That is the way it is built. Any other unit which does
not actually seize the pair (relying on dialing in) is an imposter if
it is called I/Enterphone. And no, *70 will not block call-waiting in
the case of a front door call, since again the unit does not look to
see what the CO is doing other than if the line (or rather, the pair)
is engaged then it submits its own call-waiting tone. Yes, a person on
a modem would get cut off. That is one reason I have two lines here;
one for mostly modem use, with no call-waiting on the line, period. PAT]jimmy@tokyo07.info.com (Jim Gottlieb) (03/26/91)
telecom@eecs.nwu.edu (TELECOM Moderator) writes: > Prior to divestiture, Illinois Bell (and perhaps other telcos) offered > a ... service which allowed for calls between the front door in an > apartment building lobby and the individual apartments > Then came divestiture, and in His Wisdom, the Judge ruled that > Enterphone was just the sort of service telcos should NOT be allowed > to offer. Patrick intimates that this was (another) flawed decision by His Wisdom. On the contrary, I agree that telephone companies should not be involved in this type of service. There is no reason to involve your telco in the unlocking of the front door to your apartment building. This is ridiculous. This is clearly an application where on-premise equipment makes much more sense. Besides, it was hardly just making use of some features of existing switching equipment. Rather, the whole thing was a huge kludge. > One disadvantage to this system was that the pairs coming to the > building had to be expressly dedicated > In the central office itself, there were jumpers between the Enterphone > device and the frames, and these had to be tagged with warnings not to > swap them out > Another disadvantage was that if something went wrong en-route > to the building; then this caused the apartment building front door > to go out of service And then there was the cost: > So, a fifty unit apartment building would pay about $115 - $120 per > month for the service. Not to mention that initial installation had to be on the order of several (or more) hundred dollars along with a Basic Termination Charge. > the 'common-equipment' which had previously been located in the > central office, renting for $50 per month started showing up in the > basement of apartment buildings ... at somewhere around $2000. Sorry, but that sounds like a much better deal. > The service functions the same as the old Enterphone ... there is > no longer a charge for each apartment line. Nor is there a charge > for the lobby phone or the circuit and relay to open the front door, > since these things now belong to the apartment building itself. As it should be. Let the telcos concentrate on providing better interconnection between me and the world. I'll handle the front door, thank you. Keep up the good work, Judge! [Moderator's Note: I must agree with you I think the sytem works much better as CPE than it did under the old arrangement, although the old arrangement was better for a small landlord who could not afford the initial cash outlay. IBT allowed the installation costs for Enterphone to be spread over twelve months if desired. PAT]
dave@westmark.westmark.com (Dave Levenson) (03/31/91)
In article <telecom11.246.2@eecs.nwu.edu>, jimmy@tokyo07.info.com (Jim Gottlieb) writes: > telecom@eecs.nwu.edu (TELECOM Moderator) writes: [ regarding entry-door controls for apartment buildings controlled from the central office... ] > Patrick intimates that this was (another) flawed decision by His > Wisdom. On the contrary, I agree that telephone companies should not > be involved in this type of service. There is no reason to involve > your telco in the unlocking of the front door to your apartment > And then there was the cost: >> [Moderator's Note: I must agree with you I think the sytem works much >> better as CPE than it did under the old arrangement, although the old >> arrangement was better for a small landlord who could not afford the >> initial cash outlay. IBT allowed the installation costs for Enterphone >> to be spread over twelve months if desired. PAT] If the landlord could get a mortgage on the building, he/she could certainly find financing for the CPE, and spread the initial investment over as many years as the bank would allow. I must agree with Jim, here, that this looks like an intra-premises problem, and is best solved with a CPE solution. I prefer to own my own room-to-room intercom, paging, and LAN devices, and buy the external networking from the utility. 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