Prior to T-Mobile’s upcoming Friday launch of the iPhone 5 on its network, the carrier has announced a trade-in deal for iPhone 4/4S users. Qualified customers trading in an iPhone 4 or 4S can get the iPhone 5 for $0 down. A credit of up to $120 may also be offered, depending on the trade-in value of the device — the credit could be used on monthly payments, an existing T-Mobile bill, accessories, or the purchase of another device. T-Mobile’s standard offer for the iPhone 5 without trade-in is $100 down, and $20 monthly payments for two years. The offer lasts through Father’s Day, June 16.