Unfortunately, I didn't fully understand that a "locked" phone meant before I applied to US Mobile. So I found out that my phone was "locked" to my previous carrier. If I understood this before I switched I would have purchased a new phone or unlocked my old phone in time for my service to be available to me at the time of activation. Meanwhile, I'm a little delayed using my service because I need to acquire a new phone / unlock my old phone. I am without service during this time temporarily. I attribute this problem to my failure to understand how cell phones work. Probably I missed the tutorial or FAQ on the topic. I'm still satisfied and I look forward to finding the perfect phone for me at the store today! Cheers!