You can't use it as Makkahn said. But your dad can buy a phone for you. Your dad have 2 options. He will use his positive tab and 1: pays rest of amount - his tab balance will be 0 2: put up to $360 on the tab - he will pay $15 per month tab charge for next 24 month. In both cases, he will be in the new tab system, so he won't be accumulate positive tab after this.