The issue appeared to impact the OnePlus 5 and other manufacturers’ devices, across a number of different regions of the world with corresponding emergency service numbers. Although other handsets appeared to be impacted, the press picked on OnePlus as causing the issue – but it appears the issue is far deeper.
The Chinese company explained that the issue only impacted those devices where the call was being placed over a VoLTE connection, that being Voice Over LTE, and only where the OTDOA network protocol was used. OTDOA is short for ‘Observed Time Difference Of Arrival,’ and is a location-positioning service used by some carriers and their local emergency services to determine where the handset is placing the call. However, not all carriers implement the OTDOA system, and not all carriers use VoLTE. For the bug to cause a reboot, both of these circumstances needed to be present.
Once OnePlus had ascertained the issue, they have worked with Qualcomm to resolve and patch the bug at the modem software side of things. This issue was quickly rolled out to OnePlus 5 customers. Yes; this is a serious problem with potentially life threatening issues, and yes it should not have crept past OnePlus’ testing processes. We saw a similar issue back in April where some models and carrier combinations of the Moto G5 Plus were unable to make 911 calls on Verizon. In this case, Motorola released a fix relatively easily.
The emergency calling bug also calls into question the standards that our carriers apply when assessing and testing devices for compatibility with their networks. VoLTE needs a compatible and approved device for a given carrier, but it appears that carriers did not check the OTDOA protocol. For software patches, hotfixes and updates, OnePlus has made great steps forward: compare and contrast with Samsung for instance, who recently released a software update designed to help reduce software lag on their flagship Samsung Galaxy S8 – almost six months after the device went on sale.
SOURCE [OnePlus Forums]