POTS Problem

Hello, all. In addition to cellular service I still maintain a copper-back-to-central office phone line at my residence. I've had this
for about 40 years and never had any problems - until now. Here are the symptoms (same behavior on any one of 3 extension phones):
1. Phones ring as expected in response to calling party 2. Called party (me) can hear calling party 3. Calling party can't hear me 4. DTMF (Touchtone) phone keypads produce audio tones but won't break dial tone.
I've got a call into Verizon on the above but am scratching my head as to what might be causing all of this. Your thoughts would be most appreciated. Sincerely,
--
J. B. Wood e-mail: arl snipped-for-privacy@hotmail.com

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Verizon and a landline? Good luck.
I once had almost those exact symptoms, but only on the coldest winter days. I called the phone co several times and each time they found no problems after it warmed up. I finally had to call them pre-emptively when the weather forecast predicted a really cold day the next day. They did check the line that day and finally they fixed the problem.
Also, in my case, if someone called me when it wasn't working, it would work for a few minutes. I am guessing the ringing voltage blasted through or warmed up a corroded connection somewhere.
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On 07/06/2016 12:56 PM, Michael Moroney wrote:

Hello, and another reply I got to my OP suggested it might be something broken in the transition from 2-wire to 4-wire as would be done in phone line repeaters. IOW, the upstream (me to calling party) is being severely attenuated while the downstream is OK. That would account for voice frequencies (speaking and DTMF) of insufficient level by the time they get to the CO. Despite the fact that the DC current loop from the CO appears to be intact. I wouldn't be surprised if routine maintenance has fallen by the wayside with the telco wishing these old all-copper circuits would just fade away. Sincerely,
--
J. B. Wood e-mail: arl snipped-for-privacy@hotmail.com

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That is exactly what it has to be. The 4-wire conversion is done in the line card. That may or may not be all the way back to the switch, and could be at a remote unit between you and the switch. It is located wherever the end of the "copper" is.
The DTMF detector, digit register, and the 4-wire conversion take place at that point, and is just past where the loop current and dial tone are applied.
Obviously you do have DC continuity to the line card, otherwise you would not get a dialtone. Not being able to break DT indicates no voice continuity out of the line card. The DTMF detector and digit register are shared resources that, like a connection to another line, are switched in as needed. It's the output of the line card or the switching matrix that is broken.
It is almost certainly a bad line card, and if somebody actually gets around to doing it will take a minute to test and 3 minutes to replace.

Yeah, that's probably true! :-) They don't really make a lot of difference though.
--
Floyd L. Davidson http://www.apaflo.com/
Ukpeagvik (Barrow, Alaska) snipped-for-privacy@apaflo.com
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