For some reason I have lost 1 of my 2 phone lines on the second floor.
This would be the yellow/black pair. If I am correct, the jacks on the
second floor start with the one in my bedroom. Directly below this is
my office, which works. I don't understand why this would happen, I
have done nothing to the jack in my office, it has never been out of
the wall. So, I want to test for continuity between these two points.
I don't have a tone generator, and don't want to buy one just for this.
I'm wondering if anybody has another idea short of running a long wire
from upstairs to downstairs.

Thanks,
Jim