If you ever sell a Verizon, Sprint, or other CDMA phone on eBay or another online website, make sure you never give away the ESN number. The ESN number is normally behind the battery of the phone and it is used to activate the device on an account. Most buyers want to make sure that the phone has a “clean ESN” and is ready to activate. If a phone is stolen or you stopped paying the bills on your account, the wireless carrier will flag that phone and make it so nobody can activate it.
Although most buyers are simply asking to make sure the ESN number is clean, there are some people out there who want to cause trouble. If you supply somebody with the ESN number for a phone, they can activate it on their account. If it continues to be activated on their account, they can either report it stolen or stop paying the carrier bills… The carrier will then flag that device and it will never be able to be activated. Consider the ESN number on a phone its social security number.
Even if the person is the winning bidder, I would still keep the ESN number to yourself. Never send the ESN number in an email to somebody you don’t know. Wait for them to pay for the auction and then send them the phone in the mail.
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