receiving a brand new phone in the mail with no service and I can't get my phone unlocked

So I got a T-Mobile device brand new in the mail and when I tried to connect it to use it service which I have no idea where the source is from or whereabouts of the phone at all the service has been used already and I can't get the phone unlocked when I really need a device help me unlock my phone

If I’m reading this right. You are saying you randomly received a phone in the mail and you trying to use it or get it unlocked. Just being the cautious person I am I would not try to use it. But that's just me. The potential here could lead to catastrophic results. 1st off did you order this device or did it just show up on your door? 2nd you say the service has already been used. Was that by you or someone else? As far as getting it unlocked I really don't see that happening unless you can prove you are the owner of this phone.