can you use an existing coax to run a phone line? i have coax from attic to wall jack, i have phone lines in attic, can i convert coax to use phone line?

yes...you need a balun from coax to twisted pair.

We still use string

ya, the string that's in the cat5 works great if you need 1 extra line

No, that won't work. A phone line requires two conductors but has a DC component. Baluns convert and transmit signal, but only AC signal. The DC signal will essentially be shorted. A balun on a phone line will look like a phone that is always off the hook ( = busy).

Believe it or not, just use the coax. It will work like a charm. Coax has two conductors, and the phone line does not care about the physical layout, impedance, or much of anything except that they aren't shorted together.

Choose whatever kind of connection or adaptor you like, and assign the shield to be one wire, say the white/blue, and the inside lead to be the other wire, say the blue/white. Just figure out mechanically how to connect it to a phone jack and you are done.

there are baluns for this...FYI...maybe they are not technically "baluns" but they accept coax and give you terminals for twisted pair...available at ADI specifically for this purpose.

What brand? What are they if not baluns? If a product accepts coax and gives me terminals for twisted pair, nothing about that says that it will pass DC.

And, in general,

baluns are expected to respond to the lowest frequencies in the audio spectrum, but not to DC.

even the term "twisted pair" is used to refer to the noise rejection characteristics of a cable pair carrying...alternating current of some type, not DC.

The issue still is that if a product is designed for audio and/or video, ther is no reason to design it or build it to pass DC.

With no DC current, the phone company thinks your phone is hung up. When you go off hook, a current in the neighborhood of 15 mA flows, doing two things:

telling the phone company computer you are off hook, which they respond to by sending you a dial tone, and

providing DC voltage and current to operate the phone. Even if the phone is a modern powered one, the voltage referred to in phone lingo as "battery" must be present for the phone to work.

That first reason is why a balun, which probably looks like a short circuit at DC, would make your phone look constantly busy. Baluns can be made, for more money, NOT to look like a short, but why would a manufacturer raise their product cost and hence selling price for DC, which is not part of an audio or video signal?

Ernie, am I missing something here? Are you saying you can't run phone over cat 5? We do this all the time.

I think that what was suggested is not a true balun by your definition, but simply a conversion adaptor from coax to 2 leads which could be on a cat 5

when in doubt ...... punt

Save yourself the hassle... Buy a good cordless Phone Set-Up!

Ernie has it right. Just use the coax as a two conductor cable. It should work without any adapers. POTS lines (your standard Ma Bell dial tone) will work with just about any two conductors. The two conductors are labeled Tip and Ring.

String won't work with those new "Aluminum" cans.

Has anyone seen an adapter?

Julie?