How to activate my unactivated iphone 4 that wasn't bought on virgin mobile?

My brother gave me his old iPhone 4.It used to be on Verizon, but I can only afford Virgin mobile as of right now. I need it activated since I'm going to be traveling a lot.

The only way you can put it to Virgin mobile is if it's off it's contract.
Ask your brother, and if he says yes, ask him if it has already been unlocked.
You may have to get someone to unlock it for you. Unlocking is where your iPhone can connect to any carrier.
Maybe even Verizon could unlock it for him, but only if his contract is finished.

Sorry, you can't do this. Only Verizon phones can be used on Verizon and only Virgin Mobile phones can be used on Virgin Mobile. Even if your Verizon phone is off-contract, Virgin Mobile still can't activate the phone. If you can't afford Verizon plans right now, Verizon has a new prepaid smartphone plan for $60 per month, their cheapest plan. I'll leave the link below in the sources.