1. Make sure both the microphone and the speaker are switched on.
2. Make sure the microphone and the speaker are within the effective operation range, that is, approximately 10 meters (30 feet).
3. Open the battery compartment door. 
   
   
   
4. Using the tip of a paperclip, press and hold the reset hole on the microphone for about 7 seconds. 
   

The red light on the microphone would stop flashing if the microphone is successfully reset.