To activate a used cell phone, ensure that the cell phone is compatible with your network. If the phone is unlocked and uses SIM cards, take your SIM card from the old phone, and insert it in the new one. When you want to use a used cell phone with a new account, call the service provider, and follow the provided instructions.
To check if the phone is compatible with the network, call the wireless provider with the phone's electronic serial number. This step is necessary to let the provider company verify that there is no outstanding balance on the previous owner's account. If the used phone is unlocked, switch the SIM card from the old phone to the new one. If it does not work, call the cell phone service center from another phone, and state that you want to activate the used phone with your account.
On providing the make, the model number, the serial number and the ESN of the phone, the company gets the used phone ready for activation. The company then gives instructions to do a series of things to initialize and activate the phone. Some companies also provide online activation.
To activate a new account for the used cell phone, call the service provider to receive step-by-step instructions to set up the new account from scratch.