Problems with my new phone

[Pharcyde]

I just went to go buy a cell phone yesterday, I signed up for CellularOne out of Sierra Vista, AZ. Anyhow I pointed out the phone I wanted and the person said to try out a demo phone first before I buy a cell phone to test the signal. So all is fine and dandy, I get the demo cell and my new phone number, except when I go to use the phone... well every number I dial it just says calling and has a dial tone as if the person I was calling is busy. When someone calls me, it doesn't ring. I know its the right number I'm dialing. What's going on? Is there a setting I need to change ? BTW, the demo phone is a standard, really common Nokia, not sure which model. Thanks a lot in advance.