Electronic Serial Number

An Electronic Serial Number (ESN) is a numeric identifier that uniquely identifies a CDMA phone in the United States. When a cellular call is placed on a mobile telephone, the ESN is transmitted to a base station, and the number is used to authenticate the validity of the phone.

When a cellular call is placed on a mobile telephone, the ESN is transmitted to a base station, and the number is used to authenticate the validity of the phone in respect to the cellular service the phone is attempting to use. The ESN is embedded within the signal and transmitted each time a cellular call is placed.