A
It's a stretch to call it theft if the op owns the phone. Here in the US, some providers unlock as soon as you buy it, others make you wait for a contract to fulfill. These are contractual conditions, not criminal violations. Have a great day.Officially - you can't. Those restrictions are in place for a reason, bypassing them could be considered theft...
make you wait for a contract to fulfill
And, if the purchaser left the carrier (or MVNO in this case) and had a contractual obligation, it could be considered theft of service (the service is available, but he's not paying for it). It depends on the wording of the contract. If the contract calls it theft of service to stop paying the bill, the user agreed to be bound by that, so it's criminal. (And, in all the time I owned cellphone stores, I've never seen anyone, even attorneys, go over every line of a contract. Then just sign them, the same as people who know almost nothing about law. I've even had a few attorneys try to get out of contracts, until I pointed out where on the contract they signed [I always kept copies of all contracts that were still in force] it said that they couldn't do what they wanted to do. They might not have liked it but they understood. [One even remarked that he should have read the contract before he signed it.])With t-mobile, and att, you can buy a phone and be under contract. The phone belongs to the purchaser. It is a civil, or tort law which would be violated if the op is in one of these contracts.