What is error 310-410?

Since yesterday, my phone has been doing something crazy. It starts searching........then says NO SERVICE.....then 310-410 pops up and then it goes back to normal. In the mean time, I'm cut off during conversations and cannot get back to them quickly. It also pops straight to Speaker sometimes when I'm making a phone call and the person on the other end cannot hear me. It does it automatically. I have to either wait or turn my phone off and back on for it to work. Please help!