I had that problem with my phone. I bought it from wirefly and I guess because it was so far away the settings were completely different. I didn't have a SIM card from a previous phone and used the one the phone came with. After sitting on the phone with my carrier getting all the settings right it still didn't work. Turns out it was my sim card. Once I went to a store here and changed it everything worked fine. I'm just telling that incase you run into the same problem I had. If you have your sim card though, it should work fine depending on the phone and as a previous reply mentioned, your plan itself.