On 07/06/2016 12:51 PM, Jeff Liebermann wrote:

At both ends of the 2 wire POTS line is a 2 wire to 4 wire hybrid
circuit, which deals with seperating the audio in both directions
while maintaining full duplex operation. My guess(tm) is that the
receive part of the hybrid circuit at the Verizon end is broken. Not
much you can do to solve the problem at your end.


Hello, and that certainly makes sense, assuming we treat the DC current
loop functionally separate from the AC (voice) part. That means voice
frequencies (voice and DTMF tones) generated at my subscriber location
are of insufficient amplitude by the time they reach the CO. But voice
signals from the caller are getting by OK in the other direction. I
believe those phone hybrids used on line repeaters function the same way
as the 3-dB power splitters/combiners that I've used in RF circuits.
Sincerely, and thanks for replying

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J. B. Wood e-mail: