How to Check If a Cell Phone ESN Is Clear to Reactivate

By Mandy Slake

When you purchase a used phone, it's important to know if you can activate the phone or if it has a bad ESN. Otherwise you run the risk of buying a phone you can't use. ESN is short for electronic serial number, which is the individual identifier for each CDMA (code division multiple access) handset. If the phone's ESN is attached to an account with an outstanding balance, or listed as lost or stolen, you cannot activate the phone with the original carrier.

Step 1

Obtain the phone's ESN. You can usually find the ESN on the back of the phone, on a sticker inside the battery compartment.

Step 2

Call the carrier's customer care department. You can contact the carrier by dialing *611 on the phone or by calling a toll-free number. Check the carrier's web site for the contact number.

Step 3

Tell the customer care agent you would like to check the ESN.

Step 4

Give the customer care agent the ESN. The agent will look up the ESN and tell you whether or not you can activate the phone.

Tips & Warnings

  • You can check ESNs from certain carriers at, but it is always best to check with the carrier directly for the final word.
  • Do not buy a phone from anyone who refuses to give you the ESN. A reputable seller will give you the ESN before you buy the phone.