Here is my situation:

My phone line goes to all the rooms on the 1st floor of the house and
then up to the rooms on the 2nd floor. Unfortunatly, I can't get a
signal on the 2nd floor (it doesn't have the 50V on the line like
downstairs). So I tell myself the line going from the 1st to the 2nd
must be cut somewhere, so I decide to cut that line myself at an easily
accessible point on the 1st floor just before it goes the 2nd floor.

I did a few tests...

1) Checked the line voltage on the 1st floor side: 50V, everything ok.
2) Checked the line resistance on the 2nd floor side: infinite, so there
is no short between the wires or one or both wires are cut as I suspect.
3) On the side going to the 2nd floor, I tied both line wires together
and went to the 2nd floor to test the resistance of the line: 2.8 Ohms,
which would indicate that neither of the wires from the line is cut...

In that case, how could it be that no signal was getting to the 2nd
floor? If you have any ideas what other things I could check for, please
let me know.

Thanks,
Zwox