Yes, it is working correctly and you are right, the jack is probably wired correctly too. It is actually an old four-counductor jack, red, green, yellow, and black. The interesting footnote is that I ran into this problem again with a new old phone that was already modular but without a modular line cord. I discovered it was the line cord that was a problem even though it appears all 4 wires are in correct sequence. However, the phone dials out fine with two other modular cords.
