TELECOM Digest OnLine - Sorted: Re: PBX For Home

Re: PBX For Home
Fri, 29 Jun 2007 14:42:20 -0700

On Jun 29, 9:44 am, <> wrote:

> I want to install a PBX system (landline) in my home. I've heard,
> from sellers/installers, that you must have an individual wire from
> each jack going to where the phone line comes in (i.e. a different
> wire from each jack to one central location -- where the PBX would
> plug in). Before I order a system, I want to make sure that I have
> the proper wiring. I do not want to re-wire my home.

I'm not exactly sure of what you're saying, but first let's keep our
defintions clear: A "trunk" is the line(s) between your home and the
central office. An "extension" is one of the telephone sets in your
house. Sometimes extensions are referred to as lines, but I'd rather
use "extension" to be clear.

Anyway, historically a PBX does three functions:

1) Connects incoming trunk calls to an extension phone.
2) Connects outgoing calls from an extension to an outside line (trunk).
3) Connects extension to an extension.

To do this, all wiring, both trunks and extensions, must come to a
central place to be connected to the PBX. All extensions must have
their own wire to the PBX to be rung uniquely.

Your trunk line(s) probably all terminate in the same place in a
junction box in the basement, after coming in from the demarc box

However, your extension lines may or may not be unique. Some wires
may go out individually to each extension (good for your purposes),
but others may be extended from one extension to another (bad for your

> 1) How do I check if I have this wiring in my home?

You need to physically trace each extension and trunk wire. You must
know everything (where it's going and what it's connected to) about
any wire you connect to your PBX, regardless of whatever PBX you get.
In our old house, one pair of phone wires (yellow-black) contained
electric power for old dial lights--you sure don't want to hook up a
legacy set up like that to a PBX! You must be sure there's no legancy
connections on your wiring.

> 2) Most sellers say that if I do have this wiring, the Merlin Legend
> or Magix system is the only way to go. Are there any other Avaya/
> Lucent/even Nortel systems that would work?

There may be some PBXs in which the phone is addressed digitally
instead of physically. In that case you may get away with common
wiring. However, the PBX and telephone sets will be more costly.

I have no idea of modering PBX offerings. In the past, the Bell
System and others had systems designed especially for home use. For
home use a key system may be a better deal. If you plan to have fancy
phones at each extension you might be better off with a key system.
Anyway, I suspect there are vendors who produce economical modest
sized systems that might meet your needs.

Indeed, the real answer to your question is not about the wiring, but
what is it that you expect your telephone system to accomplish?

One problem I forsee in a home is that if an outside caller requests a
particular extension -- say daughter's bedroom -- and daughter is not
in her room, the bedroom phone will ring and not be answered. You
need to work out who will be answering incoming calls in your family
and what switching will be done in response. Unless your house is
extremely large or you are talking about a large property with out
buildings, people will tend to just yell for another family member
than pick up a phone and dial an extension in which someone may or may
not be there to answer. (Kid in bedroom wants parent, does the kid
call the basement, dining room, living room, or kitchen? Easier to
yell than make 3 calls.)

Another issue is that callers may not be patient enough to work
through your PBX procedures.

One historical function of a PBX was to switch outgoing calls to the
proper trunk to save money -- perhaps a city line, suburban line, or
WATS line. But home WATS is cheap now, plus there are cell phones.

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