OnePlus 5's dangerous 911 bug explained

Most smartphone bugs are annoyances at best. Some are security disasters waiting to happen. But very few are so dangerous and potentially life-threatening than what OnePlus 5, and some Android, owners have discovered just recently. Dialing 911 in an emergency consistently causes their phones to reboot, defeating the purpose of the emergency number. To its credit, OnePlus quickly pushed out a hotfix and now it is explaining in not so many words what happened.

In typical geekspeak, OnePlus explained that the reboot was caused by modem memory usage when users on VoLTE try to dial 911, which, in turn, kicked the OTDOA protocol into gear in some cases. The presence of all these three factors (911, VoLTE, OTDOA) is what triggered the software bug.

OTDOA, or Observed Time Difference Of Arrival, is a feature used by LTE networks to help better determine a phone's location based on how long it takes the device to communicate with an LTE tower. This can be especially useful when GPS functionality is unavailable. In this case, however, that usefulness is thrown out the window because the phone never completes the call.

That said, not all emergency numbers support the OTDOA protocol even if they're made via VoLTE. In addition, not all OnePlus 5 owners use VoLTE, which is why not all owners are experiencing the bug.

OnePlus is to be commended for rolling out a fix as soon as possible, but it's still disappointing that such a critical bug passed through QA. Then again, because it was only triggered by a specific set of circumstances not present in all markets, it might have been more difficult to track. At least now OnePlus will know what to check for next time.