These wires can be purchased at your local hardware or audio video store. There are a number of ways in which a radio signal can enter a telephone. Check the handset cord to see if it has been stretched too much. Try replacing it if it has. Most of the interference to telephones occurs to the internal mechanisms of the phone.
Some manufacturers make telephones without adequate shielding from strong RF signals.
The FCC has provided a list of telephones that should be interference free. I am enclosing the list for your convenience. Wrap the power cord around the choke as close as possible to the back of the unit. If the machine utilizes a cassette tape, it may be necessary to replace it with a tapeless unit. If you hear WAER when you play your compact disc player or cassette player, most likely the interference is to the audio amplifier of the system.