ESN
(Electronic Serial Number)
A permanent 32-bit number embedded by the manufacturer that uniquely identifies a wireless communications device.
ESNs are most commonly used in phones and devices using CDMA technology. GSM phones use a simlar type of code called an IMEI instead.
See: IMEI
The ESN and a Mobile Identification Number (MIN) are both automatically transmitted to the wireless network each time the phone is used, which associates that phone with the subscriber's account and phone number.
See: MIN
In 2006, manufacturers started running out of unique ESNs, requiring a transition to the new MEID standard to replace ESN.
See: MEID