Busy Signal...

1793

Senior Member
I could use some help on this one. I went on a Service Call today to investigate a phone issue. Back-story, house was believed to have been hit by lighting. Cable company provides Internet, TV & phone. Modem has been replaced but the Tech. said all phone jacks were dead.

I plugged in a phone cable, 2 wire, and I had a Dial Tone for just a bit then it went to the Busy Signal. When I unpluged the cable and waited just a bit and plug back in the same thing, for a short time DT then BS.

Any thoughts you wish to share will be greatly appreciated.

Thanks
 

dfmischler

Senior Member
Location
Western NY
I could use some help on this one. I went on a Service Call today to investigate a phone issue. Back-story, house was believed to have been hit by lighting. Cable company provides Internet, TV & phone.
The phone signal to the provider is digital (VOIP), and the box that provides the jack for the phone(s) is an FXS port. In other words, the "battery" voltage, ring voltage, and local dialtone (and probably fast busy under some conditions) are generated by this box, possibly without any/much interaction from the remote switching equipment. The VOIP phones I manage at work aren't actually talking to the PBX until you actually place a call [except to register with the PBX]; local dialtone means very little (but people expect to hear it, so as soon as you lift the receiver you will hear it).

Modem has been replaced but the Tech. said all phone jacks were dead.
If the cable company provides phone service then they need to make their box work (maybe not the jacks in the house, though). If another company (e.g. Vonage) provides phone service using the cable company's Internet service then there is probably a separate box for that. If so, troubleshoot that box separately with the telephone service provider after the Internet service is working.

I plugged in a phone cable, 2 wire, and I had a Dial Tone for just a bit then it went to the Busy Signal. When I unpluged the cable and waited just a bit and plug back in the same thing, for a short time DT then BS.
Is it the normal busy, or the fast busy signal that means no service? The box may be unable to talk to the phone switching gear either because of a hardware failure or even just due to having a corrupted configuration.
 
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Smart $

Esteemed Member
Location
Ohio
How short a time between DT and BS?

I believe most VOIP systems detect an open, not-in-use line. For example, I have Vonage. If I do not dial any number in about 20 seconds the DT changes to an intermittent tone (call it a new-style BS). If I do place a call and the other end disconnects and I do not, after a few seconds I get a disconnected signal very similar to old-style BS but louder.
 

1793

Senior Member
How short a time between DT and BS?

I believe most VOIP systems detect an open, not-in-use line. For example, I have Vonage. If I do not dial any number in about 20 seconds the DT changes to an intermittent tone (call it a new-style BS). If I do place a call and the other end disconnects and I do not, after a few seconds I get a disconnected signal very similar to old-style BS but louder.
I could get a DT once, then hang up or disconnect when I tried a second time that was when I got the BS and I could not get a DT until I unplugged the cable.

The house is wired with a 4wire cable. I was able to make a patch cord that took pins 4,5 at the source and moved to pins 3,6 then another patch cord for the phone jacks that took pins 3,6 back to 4,5 to the phone and everything worked normally.

I guess I don't know how I could get a DT for a bit then lose it.
 
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dfmischler

Senior Member
Location
Western NY
I guess I don't know how I could get a DT for a bit then lose it.
I suspect this could be explained by either damaged equipment or wiring.

Does the phone equipment work if you plug your phone directly into the FXS port (i.e. bypass the house wiring)? If not, get the cable or phone system people to fix their stuff. If so then it is just a matter of fixing the house wiring. And that is the same as any plain old telephone wiring.
 

Rampage_Rick

Senior Member
Unplug everything from the wiring and check for low resistance between ring and tip. If there's a a short or low-resistance fault the ATA will think a phone is off hook somewhere, and will eventually timeout to an off-hook signal.

The Arris ATAs around here will have a solid green light when on-hook and flashing green when off-hook. You can quickly check phones by plugging them straight into the ATA and make sure they register on/off hook correctly.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Do you have a butt set or a known good single line phone that you can plug directly into the EMTA (cable modem) to confirm that the line is operating properly? If it is, disconnect everything in the house that plugs into a phone jack. Take your ohm meter and measure the resistance between tip and ring (red and green) and from each side to ground of the house wiring where it connects to the cable modem. It should be infinity.

EMTA's don't behave exactly like copper POTS lines but a short will still result in no dial tone with incoming calls getting a busy signal, a low resistance short will result in a dial tone (off hook) and incoming calls getting a busy signal. If you have more than one line on the modem, crossing the tip and ring from different lines will cause the modem to lock up with the LEDs to strobe on the front panel. With POTS that will get you a noisy dial tone.

The only thing that I can think of that will cause you to hear a busy signal is if a number is dialed incorrectly or incompletely. Is there an alarm panel? that would be the first thing to consider. If it got fried it's possible that it is dialing some digits that are not correct. Calling home is what it will try to do after the phone line is reconnected to report that the line is reconnected.

Fax machine, computer modems could be doing something similar but you should have eliminated them by disconnecting them or they should show up in your resistance test.

Other than that, is it really a busy signal?

-Hal
 
It was a high-resistance short on the pair. The OP said that he changed to the second pair and the trouble is clear. The high resistance short is enough to draw dial tone and keep the circuit engaged until timeout occurs and a reorder tone (fast busy signal) is sent. That's why unplugging and plugging back into the EMTA caused dial tone to come back for a bit.

If this really was a case of lightning, I'd suspect that the original protector is in place and the inside wiring is still connected to it. I'd disconnect all of the IWs and Scotchlok them together, thereby isolating them from the old protector.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
The high resistance short is enough to draw dial tone and keep the circuit engaged until timeout occurs and a reorder tone (fast busy signal) is sent.

That's why IT IS SO IMPORTANT to get your information and terminology correct! The OP said a busy signal when in fact it was a reorder tone. If he had known the difference and said that first off there would have been less head scratching and better advice.

-Hal
 

GoldDigger

Moderator
Staff member
I guess I don't know how I could get a DT for a bit then lose it.
The DT is locally generated, based on a closed DC path on the instrument side of the box. I would not find it unusual for the box to defer some of the broadband side connection setup until the first off hook event. At that point it fails, either because of a defect in the box or a network problem and gives you a busy or reorder tone. Since it cannot establish a network connection, it will remember not to give you even a brief dial tone until you reboot it.
JMSWAG
PS: and not the actual problem, but close.
Even without a telco drop, it is probably a good idea to incorporate a protector, but the original telco protector at/near the demarc has failed in the line of duty and should be given an honorable burial.
:)
 
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1793

Senior Member
That's why IT IS SO IMPORTANT to get your information and terminology correct! The OP said a busy signal when in fact it was a reorder tone. If he had known the difference and said that first off there would have been less head scratching and better advice.

-Hal
I apologize for not using the correct terminology, this is an area I'm not familiar with this and I'm trying to learn more.

Thank you for setting me straight. I'll be more careful in the future.

Thanks to all who have weighed-in and have been willing to help this "Old" man.
 
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