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Greg A.
Greg A., Engineer
Category: Phone Systems
Satisfied Customers: 2822
Experience:  Working with Electronics for 25+ years.
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Comcast cable, internet services work fine. One of the 4

Customer Question

Comcast cable, internet services work fine. One of the 4 extensions on the single landline works fine, but 3 of the 4 extensions have no dialtone. Interchanging the non-working extensions each to the single working extension confirms all 4 extensions work, only the wiring to the 3 extensions seems to be the problem.
We recently did have some sheetrocking work done in the garage, including near where the underground cable/phone line enters the house.
Submitted: 1 year ago.
Category: Phone Systems
Expert:  Russell H. replied 1 year ago.

Hi, thank you for contacting My name is Russell. I will do my best to provide the right answer to your question.

I will need to ask for more details, please:

- The landline must go into a phone system box, in order for your location to have 4 extensions, I would guess. What is the maker name, and model name, of the phone system box?

- Where do all four of the four extensions go, presumably in a back room, where the phone system box is?

Customer: replied 1 year ago.
The name on the coverplate, originally installed by Gill Cable company (subsequently bought by Comcast all 40+ yrs ago) simply says "Telephone", no other manufacturer or model number.There is no inside the garage distribution panel for the telephone or cable. Other than electricity, two external panels plus one large internal (garage) distribution panel, it seems all the cabling (TV, Internet) is internal throughout the house. No separate distribution point once the wiring enters the house/garage.
Expert:  Russell H. replied 1 year ago.

How many wires (aside from any obvious power cord) go into the box marked 'Telephone' ?

Customer: replied 1 year ago.
Other than a thick black cable (presumably the TV/Internet cabling) there's no other typical 4-conductor wiring entering that box marked "Telephone". Moreover, it appears (when I remove the cover plate on each of the 4 wall extensions, they are each connected with a small (~1/4 inch) grey 4 conductor wire, presumably from extension 1 to 2 etc. But I can find no entry point into the building for this wire. All the utilities are underground. BTW I'm the original owner, so nothing has been changed from new.
Expert:  Russell H. replied 1 year ago.

OK, and thanks for looking into things and reporting it thoroughly.

But: it's not the point of entry into the building that's important to the problem. It is, rather, where the four telephone lines (of which only one is working) come together more or less in one place, or connect to one box (if they do. Depends on the system!)

Four wall extensions... where do wires go from them? aside from 'outward to the 4 extensions'... I mean, where do they go further 'inward' toward the telephone system box, junction box, splitter, or whatever system you have of bringing 4 extensions together.

By the way, another question: When all 4 extensions worked fine, were they all like a 'party line' arrangement, where anyone could pick up their extension and hear, or join in with, any other extension ? if so, then there is just a splitter most likely, not a true phone system box, joining the 4 extensions together.

Also, my purpose at this point is to distinguish between a phone system box or splitter box problem, and just a coincidental bad cabling problem within the walls or within the main part of the building. Once we've found out which of the two the problem is, we can proceed appropriately.

Let me know, please. Thanks.