How to determine which line is which?

[Fabio]

I bought a new house that was pre-wired for phone and ethernet (yet not labeled well). I need a way to tell which line in the box goes to which outlet in the rooms. Is there a tool where I can plug it in on one end and then plug it in on the other end and it will tell me I have the right cable? What is that called and where would I get a good one for not so much money?


Thanks in advance.

 

[CalvinHobbes]

Something from here might work:
http://www.partsexpress.com/we...=52&ObjectGroup_ID=429