I was looking through the processes running on my iPod Touch 4G (through an AppStore app) and found a nice little app that was running. It was Called MobilePhone. If you want to see it for yourself, go buy one of those apps that frees memory (There are plenty on the AppStore, I used XSysInfo it is free for a limited time). Then look for the running processes (if yours doesn't support this, get a different one that does). MobilePhone is in the list. I think it's not an error (as there is one with the calculation of memory in the app). I think this is running because of FaceTime. If you don't see it, try enabling Facetime (setting up the email address and stuff) then seeing again.