Here is my dilemna. I currently have a home office on my first floor. I have two phone jacks, my phone line is connected to the jack underneath the desks and my fax machine is connected to the other jack in the room.

I want to move the offices upstairs, but there is only one jack available. Is it possible to connect the phone and fax machine to the one jack upstairs. Any suggestions on how to do this would be great. If there is a guide anywhere would be great too

The answer is yes. You can use one jack so they would both be on the same line. Go to radio Shack and purchase a telephone line splitter.

It looks like this and may be self explanatory.

If Fax is a separate line, and all phone wiring I know of has at least 4 conductors, and all jacks end up connecting outside, then swapping a couple of wires is all that is needed.
Red and green(or blue pair) is usually line 1,
And yellow and black(or orange pair is usually line 2.
Then, connect the yellow/black to the red and green on fax jack. A single line device connects to center 2 pins(red and green).
If all 4 conductor have both lines, and connect to red, green. Yellow, and black, then you could use a different splitter that has 2 or 3 places to plug in(line 1, line 2, line 1+2)
Phone plugs into L1, and Fax into L2.
Can you provide additional info?