This thread's discussion is locked. If it doesn't give you the information you need, head to its forum board for active discussions or to start a new discussion.
Sometimes the phone can't read the SIM, only way to resolve the problem is to take off the SIM by removing the battery and the back cover then re-insert the SIM. Now if the problem persist, try the SIM to another phone(downside is if you don't have another phone you need to borrow one or go to one of the nearest store in your area). If those didn't work then it's the SIM that has a problem, you could buy a SIM for $10 on the website or to one of the stores available in your area. To find a store, just go to the homepage and beside the login you'll see Find a Store.