To check for phone taps, observe keenly for phone tap symptoms such as low voice, abnormal rings and disturbing hisses. Although difficult, you have some respite in following a few steps:
Carefully Inspect Every Inch of Phone Wire in your Home: Look for phone tap equipment on the phone line like coil taps or induction coils.
Open up the “restricted” Side of the Box and check in there: Receiver, underside of the box is the places where tapping instruments are placed for their insusceptibility. It might spring a surprise or two.
Some of the more advanced Taps can be very small and easily fit inside a phone so that detection is all the more difficult. You have to have a surgeon’s eye to detect them. Alternately, you can use a watchmaker’s glass, too.
Are My Telephone Lines Being Unofficially Tapped?