In most cases, it's easiest to run the cable through the basement or crawl space, drill a hole in the floor underneath the jack and pass the cable through the hole.
How to Tap Your Phone Line:
They are usually attached to the base of the phone or the back of the handset and are a most effective phone tap eavesdropping device since they gain the signal inductively.
If it's a pure DSL line, the cover will probably be labeled as such.
Description: If this has happened, you won't be able to run a second line thru the four-strand wire. This device is available from the following: