Atomic Clock & Watch Accuracy Tool (with NTP Time) :: Android Apps by Tomáš Hubálek
android - How can I get the "network" time, (from the "Automatic" setting called "Use network-provided values"), NOT the time on the phone? - Stack Overflow
GitHub - Free-Software-for-Android/NTPSync: NTPSync is a simple NTP time synchronization app for Android.
Automatic Time Detection | Android Open Source Project
Taking a closer look at the NTP pool using DNS data | APNIC Blog