Now that just about every airtime provider is rethinking its mobile data plans, with most putting an end to unlimited contracts, it looks like iPhone users are paying more attention to their bills, and in particular how much data they are using.
A large number of users in the USA and here in the UK have discovered that their iPhones are apparently sending large chunks of data during the wee small hours using the 3G network.
A lively thread on Mac Rumours is brimming with theories, both conspiratorial and otherwise, as to why an apparently inoperative iPhone would mysteriously transfer as much as 60MB of data while its user was tucked up in bed.
The simple fact of the matter is - as far as we can tell - that the iPhone's push notifications and other small transfers of data are totted up throughout the day and the total for all of those notifications is added up after dark and sent to your airtime provider while your phone is sleeping. If these tiny amounts of data were individually listed your bill would probably be the size of a telephone directory.
The reason it is using the 3G network rather than Wi-Fi is that all iPhones up to and including the 3Gs turn off Wi-Fi push functionality while the phone is in sleep mode, in order to preserve battery life. The iPhone 4, incidentally, has better power management so will not need to do this.
Of the hundreds of posts currently on this and other forums, there are a few unexplained anomalies, and AT&T has even refunded a small number of users who have seen unusual an unexplained activity on their data accounts. But telecoms providers send out millions of automatically-generated bills every month and to expect there never to be a mistake is hopeful to say the least.