Model : Nec N342i
 
1 - Switch ON your phone without SIM Card,
 2 - Compose : **00012*CODE#.
 
Model : All others NEC
 
1 - Switch ON your phone without SIM Card,
 2 - Compose : #7320*CODE#.
 
Model : old NEC
 
1 - Switch ON your phone without SIM Card,
 2 - Compose : #3210*CODE# and press Call Button.