A cell phone provider will use a cell phone's International Mobile Equipment Identity number to blacklist it and prevent it from being used if it is stolen. Another cause for blacklisting the cell phone could be the registered owner not paying his bills on time. When you purchase a used phone, you should check to make sure it's not blacklisted by calling the service provider with the IMEI number. If you report your phone as stolen and then find it, you will need to contact the cell phone company to unblock your phone.
Call your service provider's customer service number. You need to let them know that you are in possession of the blacklisted phone, or they will not reactivate it. However, if the phone was reported stolen and you are not the original owner, they may be unable to unblock the phone.
Use your Social Security number, address and cell phone account number to prove your identity. Some providers will not confirm your identity over the phone if the cell phone has been blacklisted.
Go to the nearest retail outlet for your cell phone service provider. Bring the blacklisted cell phone, a copy of your contract (if you have it) and personal identification. They should be able to confirm your identity and reactivate your cell phone.