Government agencies do not "Tap" phones in the way you think. If a Govermnet agency is indeed tapping your calls, it is being done at the Telephone Companies Central Office and in fact, you would never know.
All that being said however, if an individual is interested in you, equipment will have to have been installed on the wiring of your home, or possibly, on the pole near you.
In any event, many cheesy systems will in fact broadcast on the FM Radio band. One easy way to find out if this is the case is to make a call to CO test tone by dialing XXX-0020 (where XXX is your prefix)or XXX-0022 (usually, it changes on many systems) and sweeping across the FM radio spectrum with a radio listening for the tone. Freepmail me if you need more info.
knews hound