How to Check If an ESN Number Is Bad

By Valerie Lauer

A cell phone's ESN (electronic serial number) must be valid to activate the cell phone. If you have any issues activating a new cell phone, it is possible your ESN is incorrect, active on another line or has been reported as lost or stolen. To avoid activation issues, research the ESN assigned to a cell phone before you try to use the phone.

Step 1

Locate your cell phone's ESN by removing the back of your phone and the battery. ESNs are either in hexadecimal or decimal format, and are interchangeable with a device's MEID (mobile equipment identifier).

Step 2

Contact the customer service department of the cellular provider you want to activate the cell phone with. Do not call from the phone that has the ESN you are checking on.

Step 3

Tell your provider that you want to check the status of an ESN to make sure you can activate it. Read the ESN from the device exactly as it appears on the back of the phone.

Step 4

Ask your cellular provider why the cell phone ESN is bad, if applicable. In some cases bad ESNs can be corrected and the device may still be usable.

Tips & Warnings

  • ESN numbers are also available inside many cell phones. See your device's user manual for instructions on viewing the ESN on the device's screen.
  • Check the ESN of any cell phone you are purchasing online to make sure it is not a bad ESN.