Guys, We tend to concentrate on the Electrical side of Services to Resi and Commercial places. I'd be interested to know what comes in as standard from your Telco or in places where you have worked?. A wide open question I guess, but is it any les important, in these days of high-speed communications?.
Study Guides for VDV / Structured Cabling Installers
Telephone service at the customer end hasn't really changed much since the 20's. The media has improved but the basic POTS is regulated to the point that it can't change. Al Capone's candlestick phone will connect and dial on a DSL line. The central office changed from several floors of clicking relays to a small box humming in the corner and the trunks are digital fiber but the last hundred feet from the concentrator to the house is still a copper pair with a 10-48v analog signal on it. The unbundling of "Ma Bell" and the rise of consumer owned equipment created the Demark box on the outside that has a RJ11 plug in it so you can isolate the "house" side from the Telco side for troubleshooting. If a phone works in the Demark, it isn't the Telco's problem and they will charge you a stiff service call fee (~$135-150US)if they come out.
Re: Most Common Telephone Service?#160300 10/06/0510:39 AM10/06/0510:39 AM
Gfretwell is mostly right about the residential end of things with the except the newest thing is Voip service being available to the residential customer, something I have switched to just recently, I get my telephone service form my cable television provider. I cannot tell the difference between the circuits when I am using it. The only real concern I had is if the power goes out I would not have dial tone, so I put in a ups for the cable modem.
As far as business service goes it has come a long way away from the old clicking relays to high speed data circuits transmitting voice digitally like PRI which can be pumped into a phone system and give you 100 lines from 1 circuit. Where I am we have a PBX (about 4000 phones and 3000 DID's) equipped with Voip and have IP phones at some remote sites that connect via the ethernet network (which is tied to our main site via T1's) this enables us to dial direct 4 digit extension's to sites that are miles away. We also have OPX circuit's that allow us to put extensions from our PBX at remote sites.
Other sites we have our own tie lines for voice and have remote shelf's full of cards(emulate cards at our main site) that are connected to our PBX and I can do programming on the phones from my desk and the phone is on the other side of town.
There are a multitude of different way's business's can configure and interconnect facilities to behave and give functions just like as if the people were sitting in another office at the same site but they are actually on opposite sides of the globe. These types of services often pay for themselves when compared to paying long distance charges if there is a heavy call volume between the sites that need to communicate.
We have a MUX installed at our site that is fed with fiber from the street and breaks down our digital circuits to copper from the fiber. Gone is the old metal can with a rat's nest of cross connections except for a couple of random DSL lines and emergency POT's lines we have in case of emergency which we would be reduced down to a system of phones that are placed in strategic locations to enable calls to be made in the event that our switch is not functional.
If disaster strikes, which it hasn't yet (fingers crossed) we would flip 6 toggle switches and the phones which are normally fed with extensions from our PBX would have their feed transferred to one of the backup POT's lines. Basically a manual transfer switch for telephone service.
[This message has been edited by mkoloj (edited 10-06-2005).]
Re: Most Common Telephone Service?#160301 10/06/0503:57 PM10/06/0503:57 PM
The service is the same, wiring and connection methids have changed. In the (not too) old days the inside wiring was 3 or 4 wire "JKT", previously it was an open twisted set. It has evolved into 3 pair cat3, or 4 pair cat5. The custoumer termiation inside evolved from hardwaired, 4 pin plug to RJ11. Outside, we had a protector made by Reliance elcetric, which had fuses and carbon blocks. The repaced it with a smaller plastic one when I got highspeed (they had no problem with the fact I had cat 3 wire). Where I am ( smaller independant phone company), they don't use "NIDs", at least that I've seen.
Re: Most Common Telephone Service?#160302 10/11/0502:19 PM10/11/0502:19 PM
Starting before 1974, Bell prewired new construction houses with 5 or 6 twisted pair cable that would likely meet the specs for a Cat2 or a Cat3 cable if tested.
With the breakup of Bell in the early 1980s, responsibility for prewiring of new construction houses fell to the electricians who mostly used the commonly-available 4-wire, non-twisted, "JKT" cable for telephone prewires.
According to information I've read, that 4-wire cable was designed and intended (by Bell) for useage on retro-fit installations where the wire would be exposed along a baseboard (the non-twisted construction and 4 wires resulted in a small diameter, smooth, perfectly round cable which looked acceptable against a baseboard). Anything that was a pre-wire install (where the cable is concealed in the wall) was to use 5 or 6 twisted pair cable.
Since about 2000, the FCC rules specify that Cat 3 cable is the minimum acceptable for telephone wiring (for new installations).
[This message has been edited by brianl703 (edited 10-11-2005).]
Re: Most Common Telephone Service?#160303 10/11/0509:14 PM10/11/0509:14 PM
If you are as old as me you remember Ma Bell invented JK. It used to be ~22ga 3 wire and it didn't really become 2 pair until the Princess phone (It's little, it's lovely and it lights) The yellow/black was the light, from the first wall wart. Twisted pair started when multiple lines became an issue, usually in apartments. Most single family phones still got wired with R/G/Y/B untwisted wire into the 80s. Computer modems and 2 line service brought the Cat 3 wire.
Re: Most Common Telephone Service?#160304 10/12/0511:58 AM10/12/0511:58 AM
Domestic lines right up until the early 1980s here were often installed as a single-pair using a type of cable which looked very much like zipcord (except it was solid-core).
Multi-pair cable is now installed as the norm, but as far as the Telco goes, they run to a single master jack in the home, and that's as far as it goes. Anything beyond that is entirely up to the homeowner to arrange and install.
Re: Most Common Telephone Service?#160305 10/12/0512:07 PM10/12/0512:07 PM
The standard in the US is the telco stops at the Dmark on the wall outside. There is an RJ11 in that box that "the house" plugs into. If a phone works in the Dmark it isn't a telco problem, unless you pay the extra couple bucks a month for an "inside wiring" service contract. A service call caused by "inside wire" without that contract is well over $100US.
Re: Most Common Telephone Service?#160306 10/13/0508:33 AM10/13/0508:33 AM