I don't have a smartphone and know little about their operation. I need an answer to a question for something I'm writing. I assume the typical smartphone has what is called a lock screen, requiring a passcode or other ID, to protect one's private info. My question is, does the lock screen also prevent some other person from using the phone to make a phone call, specifically to 911 in an emergency. Alternatively, is there always a lock screen, or can someone typically just pick up someone else's smartphone and call 911 on it? I've tried to find this out on the Web but to no avail. Even though we're talking about a phone, the articles I find say nothing about making phone calls. It's all about personal info, photos, apps, etc. Like the last thing you want to do with a smartphone is make a phone call.