There is new concern shown by OnePlus 5 owners as allegations appear on reddit of phones rebooting when dialing 911. The cause of the bug is currently unknown, however OnePlus is in contact with those experiencing the issue to try and solve the problem as soon as possible.
https://www.notebookcheck.net/Some-users-report-OnePlus-5-crashes-when-dialing-911.235476.0.html