Went to Cabo with my V400 and we had error messages everytime we tried to use the phone. Something about no being authorized for that service? I went online and read something, and correct me if I am wrong, that anytime you go out of the US you have to first call customer service to let them know and they can give you some special access code, that has to be used every so often while you are out of the country. is this true? If not, what do i need to do when trying to use the phone from Mexico? The people who had T-Mobile had no issues at all.