I am trying to add a telephone jack in my family room so I can plug in a computer modem. I ran some CAT 3 cable from a junction to the wall. There are three cables comming off this junction point to other phones throughout the house. My new telephone jack appears to be working fine (I have a dialtone) but when I dial a number and establish a connection, then I start hearing a loud buzzing noise. The other jacks that run off the same junction point have no problems. My problem must be in the wiring I just installed. Is CAT 3 not sufficient for a regular phone line? Could I have some of the wires crossed? I don't have that much experience installing phone lines so any help would be appriciated. Thanks.