A private investigator writes...
“I have multiple clients that wish to determine whether or not they are the subject of a possible central station drawn loop phone tap. I am looking for the technology to detect such phone company taps and subsequently to defeat them if they exist.

Time is of the essence so I'll look forward to your reply.”


As they say in Brooklyn... Fugetaboutit.

Sorry about the bad news. Here are the reasons...

1. Central office assisted taps these days are 99.9% court ordered law enforcement (or legal telco security) wiretaps. Subjects of these investigative efforts do not make good clients, or for good relations with law enforcement (which I am sure you desire).

2. These taps do not affect the electrical characteristics of the line. There is nothing to detect.

3. These taps are now provided to law enforcement (under the CALEA law) in a very automated way.

On the plus side...
Illegal street loop wiretaps can often be detected by an experienced technician with the proper instrumentation. This is not a do-it-yourself project, however, and outside the scope of your question.

Hope this helps. Don't shoot the messenger. Enjoy the weekend.

Kevin