謝謝你寫的這麽好的文章。的確，手機顯示沒有service provider的信號時也可以打911。因為這時候，手機會自動找到那裏的最強的信號。
you can make emergency phone calls without a network signal. When your phone loses signal from your provider's network, it automatically connects to the strongest network that it can find in order to allow for emergency calls to go through. However, since it is not your network, you cannot make other calls.
https://survivalfreedom.com/do-emergency-calls-work-without-signal/
