Great question tweet314!
You can activate it with the existing information, but it won't be yours. It will also disable access to the App store unless you know the previous persons login credentials. It may not be the full iPhone experience a user really wants. If you want to go ahead and wipe out the phone so its like brand new follow the steps below to reset. You can also login to vzw.com/myverizon to activate the iPhone, or dial *228 SEND to activate! I'm here if you have additional questions.
iPhone 4 hard reset: http://bit.ly/Rnq9mu
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