Someone is spoofing your number when they call. Not much you can do but go to the FCC and tell them someone is spoofing your number making unsolicited calls, and in turn receiving calls.
change your number
It's not T-Mobile's fault and it's not your fault. The telemarketers pick numbers at random and use (spoof) that caller ID. I regularly get SPAM calls appearing to come from numbers in the same T-Mobile CO-prefix (exchange) as my phone. I even get SPAM calls from myself. The phone companies need a stronger caller ID system that can't be spoofed. But by now people should know about this and ignore the caller ID.