Sprint locked my iphone can I jailbreak it?

Sprint d/c my iphone b.c bill was too high & couldn't afford it. I called in to cancel services they said on the 20th. However, customer rep told me that I wasn't able to use my iphone (locking it) & wasn't able to activate the phone, and I'm wondering if I unlock my iphone will I still be able to use my iphone since I haven't paid my bill with sprint?
I'm new at this so I have no clue.

Added (1). Now what if I pay the outstanding bill can I still jailbreak it? Eventhough if I have a contract with Sprint?

No, it won't work
when you have an outstanding bill, the phone gets blacklisted
its illegal for any wireless company to activate it on their network.

pay the bill, or loose the phone

Yes if you pay for the bill, then you can jailbreak it.