My venerable self-installed Panasonic KX-T30810 has worked fine at home for almost 30 years. But recently one of the three CO lines won't generate a dial tone, regardless of which CO port on the KX-T it is plugged into. The other two CO lines work fine on all three KX-T ports.
I suspect that AT&T recently changed my physical copper pair, or what it is connected to in their CO. The killer is that the new line works fine with a modern touchtone phone, so of course the AT&T tech resolves my trouble report with "no trouble found" and says the problem is with my equipment.
When I use the KX-T to dial on the line without a dial tone, I get CO error messages like "Your call did not go through", or "It is not necessary to dial a 1 when dialing this number". If I just leave it off hook without dialing anything, it says "Your call did not go through" rather than the usual "If you'd like to make a call...". So the CO line is seeing something, but not liking what it sees.
I measure the on-hook voltage at the DMARC as 51.9V, and the off-hook voltage as 6.8V.
Any idea what's going on? Is there some modification I can make to the KX-T to make it compatible with the new CO line? Is there some way I can describe to the AT&T tech how the CO line needs to be different, or what's wrong with it?
Len, an engineer end-user
PS: Sorry for posting in "General", but I can't figure out how to post in the Panasonic forum.
