With good batteries inside, hold the handset to unlock the key pad. Then press and hold
the SET button (around 10-15 seconds) until the red and green lights are flashing.
They will flash for up to 10 seconds.
While the red and green lights are flashing, open up the battery compartment on the
handset and remove one of the batteries for about 10 seconds.
Replace the battery and the battery cover.
Now when you hold the handset the green light should be flashing faster (several times
a second), the handset is now reset and ready to be paired.
(Note: If the red and green lights do not flash together, then the handset is probably
already reset and ready to pair again.)