Extended Networks iPhone

I'm in a dead zone for Verizon. When I try to roam off of Golden State Cellular, and yes they have a contract for Verizon users to roam off of them, whenever I try to make a call I get a message saying my phone number isn't recognized and I'm not an authorized user. Other than this problem, when I'm on a Verizon tower, everything works fine. But this just stinks. Yes I'm moving soon, but I will be visiting back home and I'd like my phone to work. I've talked to Verizon and to Golden State and all they do is blame each other. Does it sound like maybe it's the device or something?