Blacklist and Unpaid Bills are two different things. If your iPhone is BLACKLISTED by T-Mobile USA, then a cleaning service will be needed. If your iPhone is simply tag with Unpaid Bills, then it is not possible to remove that (The unpaid bills is in the account, not the IMEI number), but you can unlock it to start using it with a different network. In some cases, an iPhone can get BLACKLISTED if the unpaid bills amount is very high. On this case, a cleaning service is required (To remove the Blacklist status - But the Unpaid bills will remain) and then you should unlock it (To be able to use other networks). If you have no idea what of the above is happening to your iPhone, then please use our iPhone IMEI Unlock Check service from our Home Page, to figure out what is going on!