I don't think the iPhone nor any Android phone have the necessary circuitry to receive the WWVB signal directly. THey do, however, keep time sync with NTP or so

I don't think the iPhone nor any Android phone have the necessary circuitry to receive the WWVB signal directly. THey do, however, keep time sync with NTP or some NTP-like service over the wireless network or wifi. That should keep it's knowledge of time accurate to a second or two.