Portable Phone Causes Service Dropout

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big john

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Portland, ME
A friend of mine recently lost telephone service. I don't do phone work but agreed to look at the system for her to help avoid a service charge from the TELCO. Calls could not go out or be received but ring voltage would still come through the line; the phone would ring, it's just there wouldn't be anyone there when you picked it up. There was no signal at the network interface (checked with a butt-set) but this is a multifamily and the other lines coming into the neighbors house all worked perfectly.

Called the TELCO and they suggested disconnecting all the phones because apparently a low battery on a portable phone can cause an interruption of service. This sounded strange to me, but with nothing to lose I gave it a shot. Sure enough, after a few minutes telephone service was restored.

These portable phones have independent power supplies in the form of a 12V wall-wart, why on earth would a bad battery cause service interruption?

-John
 
Some portable phones ring both the base unit and the handset. If the handset had a low battery there probably wasn't enough voltage to power the tone supply and speaker. The base unit still should have rung unless the ringer was turned off.
These portable phones are so cheap now you just throw them away when the battery gets low and it keeps the little 6 year-olds in China employed.
 
I think you hit the nail on the head. Chinese junk that either has a forged UL and FCC label or none at all. I wouldn't lose too much sleep over why it was happening, just chalk it up to what was doing it. Cordless phones and dial up modems are notorious for creating problems.

The proper way to troubleshoot problems like this is to disconnect all phones and other devices then plug in a known good regular single line phone. If your demarc has a test jack that would be the place to start. If you have the problem at the demarc stop right there, it is the providers responsibility.

-Hal
 
Thanks for the replies. Like I said the problem resolved itself so I'm not worried, just puzzled.
If the handset had a low battery there probably wasn't enough voltage to power the tone supply and speaker.
Click to expand...
Unfortunately, I don't think the problem was that simple because this wasn't the case of one phone simply not working. The service to the whole house was down, as if there was an open hookswitch, except there was still occasional ring voltage. Whatever this was must be a common problem because the operator at the TELCO suggested the fix.

Who knows?? :confused:

I was just completely stumped for answers and wondered if anyone had heard of this.

-John
 
Did you isolate the home at the NID before you connected your butt set to test for dial tone? If so, how long was it before you connected the butt set?

I've seen it where if you have a location that has had a "off hook' condition for an extended amount of time there is a delay before the Telco will reapply dial tone/battery, sometimes as much as 2 mins.
 
Have you ever had a car with a set of bad battery cells - it has 12v but not enough amperage capacity to actually start the car? (Happened twice with an old Jeep of mine - took a while to figure out that a diode in the alternator was bad and cooking/boiling the battery but still charging it to 12v and appeared to be charging at 14v. 3 batteries later...)

Anyway the hook switch may be of an SCR or other electronic type and a bad battery may have not had enough voltage to actually operate some of the cicuit in the phone - may have even damaged the phone. Good ol' amperage up due to voltage down could damage a portion of a circuit on a chip, or left it in a latched state for simular reasons. Of course there is the law of planned obsolesence - the sand ran out of the hour-glass so to speak for the phone - and not universal to items made in china or anywhere else. And/or alternately, the Telcos CO board has a number of diagnostic circuits that tell them what is going on with a line automatically - any trouble like a short, or anything that looks remotely like a short to the computer software that manages the switching would automatically disconnect the line - put into trouble mode, then test and retest it periodically untill corrected - once it saw it was OK it would reconnect. I see this often.....
 
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