In almost all cases like this, your absolute best choice is to simply give them what they want and gtfo of there. If they see you playing with something in your pocket, it could escalate things very quickly
I've often thought about "what if..." that smartphones would suck at that older phones were better at. Mostly if you couldn't see the phone (by being blinded or it's not in view).
I do notice my phone has a small 'emergency call' button on the lock screen so that's a plus. I probably wouldn't notice it in a real emergency though (I can only imagine I'd panic and forget it).
