Redial Last Incoming Call without Unlocking Phone I left my iPhone X running iOS 11 at a casino. Someone at the casino called two of my contacts while they had my phone.


1:32 Brian calls my phone to see if we can hear it
6:36 My phone calls Brian
9:32 Nancy calls my phone to see if we can hear it
10:52 My phone calls Nancy


Between 9:32 and 10:52 I miraculously remembered my iCloud password, so we already knew where the phone was and we were on our way there.

But I haven't been able to figure out how they made those calls. I assume it has something to do with them being at the top of the Recent Calls list.

I'm pretty sure (but not 100%) that I had Siri disabled. If I did have it enabled, I would have also had it enabled on the lock screen. But even in that state, I can only get it to show me the last caller and it tells me I have to unlock to make the call.

Is it possible to redial the last incoming call without unlocking?
Yes. 

Under Settings > Notifications, if you have "Show Previews" > Always along with  Phone > Alerts > Show on Lock Screen, then all you have to do is tap on the missed call from the lock screen to call it back.