I put this is the iPhone section, because half of my problem involves my iPhone 5 and because this is the section where people seem to talk about carrier issues, too. I am having problems with AT&T accurately measuring my data usage in a timely fashion, on two devices (iPhone 5 AND Novatel Liberate MiFi). Actually, this is the first month that I've had a problem with AT&T's data usage measurements on my iPhone, but I have had the problem with the Liberate for the entire time I've had it (4-5 billing cycles). Currently, my iPhone's cellular data usage meter, which is accessed through the Settings sub-menus reads over 4 GB for the month (I am on the grandfathered unlimited data plan, so this is fine). However, AT&T's website (along with the mobile app) says I've only used 1118.xx MB. It has displayed this exact number for approximately 10-15 days. Although I have "unlimited" data, I have been throttled and do not wish to experience that again; therefore, I do ration my data use a bit. What really irks me about this is that I've been told, several times, by AT&T that their information (i.e., website and app) trumps what my device says; keep that in mind for the issues with the Liberate. The data usage measurement issues for the Liberate MiFi are much worse, IMO. In this case, AT&T's measurement is ALWAYS 25-30% LOWER than what the device reports. BUT (a HUGE "but"), when the bill comes it charges me for the amount that my device reports. Also, the website and app NEVER display the "accurate" information, even at the end of the month; only on the bill. Obviously, I know now how to avoid being charged for overages, but I still question: which one is actually correct? And how do I know if I am actually getting the 5 GB, for which I am paying $50. So, anyone else experience these and/or similar issues? Thanks.