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  The fax line coming into our office is dead. I have been told to fix it. I am not a I.T. guy, just a plant electrican. I'm positive the line is dead, by using a phone jack tester.
  My fear is going into the server room and rooting around with the cables. They bought me a Greenlee 700c probe kit. I have no idea how to test the line, from the server room to the jack.
   How do I identify the CATe cable? Do I have to disconnect it or can I leave it hooked up? Even if the cable is good where do I go from there? Are there any voltage checks that I could preform ?



1. Make sure that the probe kit is working by turning it on and testing the receiver by moving it near the transmitter.
2. If the tone set (probe) is working then plug the transmitter part into the wall jack of the faulty fax line.
3. If there are numbers on the wall jack make a note of them and of the room or any other relevant information like the fax number.
4. Go to the server room and look for the cabling frames or 19" racks with patch cables.
5. See if any of the labels match your description noted earlier.
6. If no match then use the tone receiver by moving it over each cable in turn. If you pick up the tone then you are near the cable that you need.
7. If you find the cable make a note of where it is plugged in/connected up to.
8. You will then need to test the socket there to see if you have dial tone 'going away' from the server room.
9. If you do have dial tone and prove that it is the correct line for your fax then you have a cable problem between the server room and the fax location.
10. You only need one pair to work, use the probe to bring up a new pair, if the probe is connected and you short out the pair then the tone should disappear proving that it is the correct pair.
11. With the tone set plugged in the led should change if it is plugged into a working socket.
12. The default voltage is normally 50V DC for a working analogue line/extension.  


Telco default loop voltage is -48VDC, and has been for many moons!

Does the line come from your PBX or Telco?



OK...as SYQUEST asked, is your fax a physical B1 dial tone line coming from the telco, or is it an analog extension off you phone system?

If it comes from the telco, call them and ask them to come on site and check the line. If they say it is good to the Demark, ask them to make sure it is labeled at the demark and to show you where it is (this may, or may not help you trace it down).

If it comes from the PBX, then it is best tracing it from the jack, unless the PBX block or panel is labeled with the extension number of the fax). Does the jack have a number designator on it? If so, it should correspond to a number on the patch panel.

If the office is wired with cat5 or cat6, the twists in the wire makes it difficult to find your tone. The dial tone pair of a cat5 or 6 wire will be the center two pins, 4&5

"If I had known it would turn out like this, I would have became a locksmith" Albert Einstein

Mitel 3300 4.2 basic & advanced, 5000 4.0


I didn't notice the date on this when I started typing...what was the verdict with your fax?


"If I had known it would turn out like this, I would have became a locksmith" Albert Einstein

Mitel 3300 4.2 basic & advanced, 5000 4.0


Simple solution. Go to ur dmarc locate ur fax # and connect a analog phone or buttset to the lec's test jack. If you have dial tone there, then its an inside wiring issue, if you dont have tone, its a lec issue. If you do have tone and this is a stand alone line dedicated to fax only and is not on any pbx, simply connect your line tester on the dmarc side that belongs to you and put ur test probe on the fax machine end. This is were u will see what the problem is now. If you have tone at the dmarc at the lec side and this cable passes on your tester, then check ur fax machine. If the cable fails the test, check which pair failed, check the connections/terminations and possibly replace the wall jacks or cable.

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