My boostmobile phone says out of service whenever I try to send a text?

I just bought the Boostmobile i475 phone and it makes calls just fine, but I cant send a text and get on the internet? I have One bar of service and it says Out of service as soon as i click send. I have the 50 dollar unlimited plan so I know I have texting and stuff. And it will make clear calls with no bars. What could be the problem????|||the problem is that you have boostmobile