Q: I have a third-generation iPad and I want to use FaceTime and iMessage with friends who live outside of the U.S. However, I keep getting a message that says “Not registered with iMessage” whenever I try to send to them. What does this mean? They have an iPhone. Can you help? - Bill A: This error means that the number or e-mail address you are trying to reach is not registered with Apple’s iMessage servers. Assuming that you are…