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replacing an existing telphone system

replacing an existing telphone system

replacing an existing telphone system

was recently asked by a friend of mine to help them in replacing the existing telephone cabling for a 5 story office building. the existing system has seen better days. it functions but barely. here is the question:
if a new infrastructure was to be built along side the existing one, should all the cross connects be mimiced at the same positions where they are now? and should a cross connect be made from the old 66 blocks at the demarc point to the new 66 blocks  on the new system? or would the phone company come down and repunch their line to new system?
yes i am new to the world of telephone so please be gentle lol,  any help would be greatly appreciated.

RE: replacing an existing telphone system

Typically the telco only wires to the demarc and gives the company a place to cross connect their equipment to. The Telco does not want to be held responsible for any damage that might occur if things are done wrong. You will have to cross connect from the demarc to the new wiring as needed.

RE: replacing an existing telphone system

thanks for the info. there is a basement with a telco closet, my assumption is that the demarc hits this closet first. unfortunately my buddy is not sure where the demarc cabinet is.  

RE: replacing an existing telphone system

When it comes down to it - telephony wiring (analog and TDM) is just a big game of connect the dots and matching colors. So long as you have a defined path from the phone system to the phone itself, how you cross-connect it shouldn't matter - so long as that one to one relationship between telephone and phone switch port is maintained, without breaks, bridges or reversed pairs and within spec according to the phone system manufacturer.  And yes, there are industry standards that need to be adhered to as well.  

Sounds like you guys should be enlisting the help of a good telecom vendor for this project if you don't fully understand how phone wiring works.  

RE: replacing an existing telphone system

I agree with nessman, you probably want to get a vendor out to help you.
Also, the telco demarc is probably not in a cabinet, but blocks screwed to the wall somewhere, probably the basement. The demarc will have the phone numbers labelled in some way, maybe a paper tag, possibly a hinged cover over the 66 blocks etc.  

RE: replacing an existing telphone system

Unfortunately the location in the basement which seems to be the demarc, has no labeling. It seems that we would have to "reverse engineer" what lines are live. Or is there a way to test that from the demarc?
Thanks for the help so far!

RE: replacing an existing telphone system

put a butt set on each pair in turn, if you get dial tone, try calling a cell phone and see what caller id tells you.

RE: replacing an existing telphone system

Thanks for the info! I have a fluke ts19, will give it a shot and see what happens.


RE: replacing an existing telphone system

The dmarc should be easy to identify, it's a black cable comming in from the raod and "should" go to a grounded protector. As mentioned the Telco will only bring dial tone to the building. If I was the vendor asked to come in and sort this out I would be tempted to pull all jumpers and rebuild. Anyone who gets forgotten will let you know and you can quickly tone out and reconnect their line.
Is this office mostly in use or are they getting a new tenant? If it will be for a new tenant just wire it and wait.
Having a pro help you will make this go much smoother, but it would be a good idea to know what you want to accomplish before you call them in.

RE: replacing an existing telphone system

Another reason you may also want to consult a vendor or your local building inspection dept. is  that you could be held responsible for removing the old wiring system after the new one has been installed. The NEC prohibits leaving abandoned cable systems in Cieling.  


there may not be any stupid questions
but their is a bunch of inquizative idiots
(myself included at times)

RE: replacing an existing telphone system

Please, please,please, as you are doing the new install, keep good documentation, and leave a copy on site. Better yet, find your self an old set of C.O.E. lettering stamps and mark the 66 or 110 blocks. You'll make the future techs very happy.

RE: replacing an existing telphone system

From one who had to figure out the phone wiring for multiple buildings with NO documentation from the previous tech, I definetly agree with TheLymner!

RE: replacing an existing telphone system

Another number to identify POT's lines is (800)444-4444.This will work on any line. It is an MCI identifier. Once you hear the number hang up.

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