vtech CS-6309 handset
how to reset ( clear / de-register / deregister ) the handset, and made it ready to re-register | reregister to different or new base unit. ( CS-6319, CS-6329 )
#1 press [ MENU ] button
#2 enter code '*7890#'
#3 press [ MENU ] button
#4 use Up or Down button to select "TEST HANDSET"
#5 press [ MENU ] button
#6 use Up or Down Button to select "REGSTR CLEAR"
#7 press [ MENU ] button twice to select and confirm
#8 disconnect battery wait several seconds and reconnect
#9 after reconnect the battery, it is ready to register to different base again.
#10 to register to new Base , press and hold "FIND HS (handset)" for 4 seconds until red LED turn ON.
#11 it register in about 10 seconds
#12 it is ready to use now.