AppleInsider writes that some iPhone 5 owners have been reporting an unusual problem with their new phone’s cellular connection. According to AppleInsider, a bug is making some phones use cellular data despite being connected to a Wi-Fi source. Initially it was believed to be only Verizon iPhone 5s that had the issue, but now there are more complaints appearing on Apple’s customer service forums, especially since Apple released a carrier update this past Sunday for Verizon iPhone 5s, which seems to have fixed the problem for those particular phone-owners, but not for those AT&T and Sprint customers who are also now complaining. Essentially, the glitch means that the phones are continuing to use up your precious data allowance, even though the phone’s notification is telling you that it is connected via Wi-Fi. This was picked up when some iPhone 5 owners noticed that their data usage increased dramatically when they started using their iPhone 5s.
Source: Bug causing iPhone 5s to use cellular data while on Wi-Fi may not be limited to Verizon