NITZ is a function that allows cellular networks to provide time and identity information to mobile devices. NITZ stands for Network Identity and Time Zone, and it is an optional part of the 3GPP standards that define the GSM, UMTS, and LTE technologies. NITZ can transfer the current mobile network identity, universal time, daylight saving time, and the local timezone to devices via the wireless network.
NITZ is useful for mobile devices that need to adjust their system clock and display the correct time and date, as well as the network provider name, to the user. NITZ can also help with some network functions, such as billing, authentication, and location-based services. NITZ can be delivered to mobile devices at different times, such as when they register on the network, when they move to a different time zone, when the network changes its identity, or when the network has a signaling connection with the device.
However, NITZ is not a very reliable or accurate way of synchronizing time, as it depends on the network operator’s implementation and configuration, and it may not be available or consistent in all areas. NITZ also has a low resolution and accuracy, in the order of minutes, compared to other time protocols, such as NTP, which can provide millisecond accuracy. NITZ also does not support leap seconds, which can cause discrepancies between the network time and the universal time.
Therefore, NITZ is a convenient but not a definitive way of obtaining time and identity information from cellular networks. Mobile devices may use other sources of time, such as GPS, NTP, or manual input, to complement or override NITZ. Mobile devices may also have their own internal time zone software and database, which may not match the network’s time zone information.