A fact sheet issued by the Privacy Rights Clearinghouse defines wiretapping as "any interception of a telephone transmission by accessing the telephone signal itself." Wiretapping is a common law enforcement tool, and according to that same PRC fact sheet, in 2009 there were 2,379 authorised wiretaps conducted during criminal investigations. This number doesn't include terrorism-related wiretaps, nor those conducted by the National Security Agency's wiretapping program.
According to the PRC fact sheet, the majority of wiretapping devices do not produce audible sounds. Odd sounds, clicks and static during a phone call are most likely an indication of a problem with your phone line.
Ask Your Phone Company
Your first and simplest course of action is to contact your local phone company. Your phone company can perform a line analysis to determine if your line is being wiretapped. A typical line analysis can detect illegal wiretaps, room listening devices, phone line splicing, low frequency devices and wiretaps placed in wiring closets or telephone rooms.
In the event that your phone is being illegally wiretapped, the phone company will inform you after the analysis. They will not notify you if the tap is legal and warranted. In the event you are being legally wiretapped, you must be notified within 90 days after the tap is discontinued.
According to the PRC, devices marketed as tap detectors are of questionable merit. In order to detect a tap, these devices must detect electrical or signal changes over the phone line being tested.
Security Intelligence Technologies sells two models that claim to do just that. According to Gary Rogers of Security Intelligence Technologies, the CCTA-1100b uses a device called a Time Domain Reflectometer to measure impedance and capacitance levels on phone lines, as well as high-frequency signal changes. Rogers does acknowledge that the device is not meant for consumer use because of its steep learning curve and high price tag, at around £15,600 as of December 2010.
SIT's more inexpensive unit is the B-400 Tap Alert. The Tap Alert is considerably cheaper, at £1,300. The B-400 uses a masking sound to detect call activity, but it is only suited for single-line use. Unlike the more-expensive 1100b, the B-400 cannot pinpoint the location of wiretapping devices, but only confirm their use.
The Corpa Group, a licensed and bonded private investigation firm, advises that you can often see evidence of a wiretap.
Common signs of wiretapping include a break-in where nothing of significant value was stolen, slight movement of sockets or switches, odd breaks in wallpaper, moved furniture and well as brick or plaster dust on floor.
Watch for signs of remote monitoring, such as unprompted visits by utility companies or repairmen or new, empty vehicles being parked near your home or office.