Telephone line question

[sfav8r]

We don't do a lot of telephone work, but recently had a request to install two phone lines. Pretty basic stuff, we ran about 50' from the office to the utility room where the MPOE was. The telco had already identified the lines on the binding post and we connected the two new lines.

Now, a couple of days later, the client is getting a double dial tone on a different line. I stopped by and checked everything we did and it looks fine. I called AT&T for them and AT&T said they showed a crossed line, but couldn't determine if it was on their end or on the clients end. When they came out, they did a quick check and siad their end was fine and left. So now the client is calling me again.

Does anyone know what causes a double dial tone? The symptom is that you are making two calls at once. Depending upon the timing, one line goes through and you get a ring and the 2nd line gets a busy or a roll-over line. It's very annoying.

Any suggestions as to what to check or what we might have done that caused it?

Thanks

 

[TOOL_5150]

It sounds like a programming issue... problem on telco's side. To be sure it isnt your line, disconnect both sides, check continuity - should read OL or open/infinity. then tie the pair together at one end and check continuity again - it should be a closed circuit. if that test passes... it doesnt have to do with the line you installed.

I would try replacing the phone also, with a known good working phone.

~Matt

 

[LarryFine]

You have to go to the demark point, and see whether the issue is on your side or their side of it. Somewhere, at least one conductor is being shared by different pairs. You have a 'line-to-line fault' you have to locate.

 

[TOOL_5150]

You have to go to the demark point, and see whether the issue is on your side or their side of it. Somewhere, at least one conductor is being shared by different pairs. You have a 'line-to-line fault' you have to locate.

Larry is most likely correct. I saw you mentioned binding post - those are somewhat easy to hook up pairs incorrectly to if you dont deal with them often.

~Matt

 

[cadpoint]

It sounds like a programming issue... problem on telco's side. To be sure it isnt your line, disconnect both sides, check continuity - should read OL or open/infinity. then tie the pair together at one end and check continuity again - it should be a closed circuit. if that test passes... it doesnt have to do with the line you installed.

I would try replacing the phone also, with a known good working phone.

~Matt

I thought they had the little telephonie thing-a-gigs to test all that out.
a transmitter and recievier, or a one side reader of the circuits involved.

I frankly wanted to say I thought they landed twice on each ground side of two different circuits.

 

[TOOL_5150]

I frankly wanted to say I thought they landed twice on each ground side of two different circuits.

Another way to say what larry said. It sounds like he landed his pair on 2 seperate pairs.

~Matt

 

[cadpoint]

Right "X", there are a few sharp tools in the shed. The right tool for the right job, rules ...

 

[bobbyho]

Two line phone sets are a common problem as far as making a cross. The phone company should be able to do a test on your line and if the guy is good he will run the test after he disconnects your inside from the outside at the demarc. A simple MLT test (your phone guy will know what this is, mechanized line test) will show if there is a cross in the outside plant (wires). Remember phone is not like electricity in that if 2 separate lines touch one another they don't explode or trip circuits. They simply cause problems such as this of which some symptoms might be a second dial tone after you pick up your line and start dialing.

 

[LarryFine]

Two line phone sets are a common problem as far as making a cross.

Excellent point, and my mistake for assuming the obvious stuff was checked, such as a 2-line phone stuct in 'conference' mode.

Always unplug all phone cords, including faxes, modems, cable or satellite boxes, etc., when troubleshooting phone lines.

 

[KJay]

I would invest in a butt set so you can at least check dial tone and polarity at the interface and then at the jacks themselves.
Without the right tools it?s mostly just a guessing game, especially when multiple lines are involved.
Sometimes with twisted pair, something as simple as a staple being driven too hard can cause problems. Are you sure the connections at the jacks are correct?
You can?t always rely on the phone company when it comes to troubleshooting, especially when it comes to things like to PBX?s, sometimes you need to almost find the problem for them, such as when outside wiring issues are causing ground start ring backs.

 

[e57]

Larry is most likely correct. I saw you mentioned binding post - those are somewhat easy to hook up pairs incorrectly to if you dont deal with them often.

~Matt

Double punch.... Depending on how much - or little coffee you've had - even if you deal with phones often - it is still an easy mistake.... Especially if there may have been an alarm loop back to the MPOE - gets me most of the time. (Not checking to see if a pair is already being used - then punching another onto it...)

Anyway - In any troubleshooting with phones I usually take this approach.

Remove any and all connection to the pairs at the MPOE, and check the pairs there with no premise wiring at all. Usually gives you a clear direction to go - thier way, or your way... The same tells you who's problem it is. Thier way is a call to them to sort out thier mess. Your way is to go sort out your own mess.

Either way - it sounds as though the two lines are connected somewhere... And splitting the two is just finding where it was done. Sounds like there are only two places for you to check. (As it sounds like in the OP that the lines are run direct from MPOE to the jacks) The MPOE, and your jacks are the only places to check..... If it is prior to the MPOE, or the phone itself - bill for your time.

 

[goldstar]

You've got a lot of good advice so far but I'd like to add a few things. When you get to the site and before you disconnect anything, clip on your headset (I'm assuming you have one) and see if you do, in fact, have the two dial tones. If so disconnect one interior telephone at a time. If you lose the dual dial tone at any point, that particular phone would, in all probability, be the one causing the problem. If you don't lose the dual dial tone after all phones have been disconnected I would take a close look at the phone jacks. Sometimes the pins inside the jack get bent and short together causing the problem. If they all check out OK then you'll have to pull your wires off the pinch block and test them individually. If everything internally checks out check the cable running from the house to the utility pole. Bear in mind the telco is responsible for all wiring from their central office up to and including the D-mark on the house.