MaximRecoil:
Try reversing the red & green wires of the incoming phone line inside the payphone to see if that helps with your problem.
Also, it might be possible your keypad assembly (a.k.a. "coin dial unit" ) may have a wiring error.
Yeah, this morning I was thinking about reversing the tip and ring wires, but rather than doing that, I entered diagnostic mode and did the loop current test as described in the manual:
Loop Current Test..........Dial [ * ] [ 3 ], if tip/ring properly connected, Voice = "Thank You".
(Failed)..........Warble tone in receiver = tip/ring are reversed or loop current from C.O. not detected by phone.
The voice said "Thank you" when I did the test. I also tested voltage and amperage of the loop current with a multimeter; it showed ~49 VDC @ 60 mA.
Also, I have two keypads; the one that came installed in it, and a standard 61C. The one that came installed in the phone doesn't have any alternate wiring options, not even for the handset, because it is all modular:
Both keypads produce identical results.
MaximRecoil:
I was uneasy about the difference between your phone's behavior on #3 on my previous post, so I performed the test again this morning. I apologize because the results of my 2nd test was identical with yours. On an incoming call, if the extension picks up the call first, the line is dead to the payphone. I could not hear (although I'm not 100% sure my wife was speaking during the test, but it really doesn't matter anyway) or be heard. The line appeared totally dead. So I guess the final proof is that these protel phones truely can not act as an extension. It's too bad because everything else acts as expected with the added advantage of making money for outgoing calls.
The response to *#62 was also: dollar dollar + 8822000001 (same as your results)
Did you buy your phone from ebay from a guy in Alabama? That's where I got mine. They seem identical, but I'm sure there were thousands installed across the country.
Thanks for doing the test again.
I did some more tests of my own. I have 3 extensions in my house, plus the payphone. To add the line cord for the payphone, I simply connected its red and green wires to the red and green screw terminals within the modular jack that is on the wall beside my computer (then I ran the line cord under the floor and inside the wall that the payphone is hanging on). I also have a home phone (Western Electric model 2500) plugged into that same modular jack that is beside my computer. This results in the payphone being wired directly in parallel with the 2500.
My previous tests were done strictly with the 2500 and the payphone, and resulted in being able to hear on the payphone, but the transmitter was inactive and the phone would start beeping after 25 seconds and then go totally dead. However, this morning I did the test by first answering other extensions in the house (a Western Electric 554 in the kitchen and a Western Electric 500 in my bedroom), and I simply got a totally dead line when I then picked up the payphone's handset; i.e., I couldn't hear anything and it never started beeping; the same as you described.
I have no idea why it makes a difference which extension I answer first. Even though the 2500 is wired directly in parallel with the payphone; electrically speaking, the payphone is in parallel with all of the extensions; given that ultimately, I only have one phone line in the house. And like I mentioned earlier, when I disconnect the payphone and hook a normal home phone up in its place, it behaves as a normal extension no matter which other extension I answer first (which is exactly how one would expect it to behave).
I guess it doesn't matter though, because either way, the payphone doesn't work as an extension (unfortunately); I just can't imagine why it makes a difference which extension I pick up first, and that sort of bugs me in and of itself.