You need something simple and standard for emergencies, in the same way you have a three digit emergency number in the US and UK (and, I assume, other places).  If every phone is different nobody will bother learning the sequence, or they&#x27;ll remember the sequence they had on their last mobile.<p>Most people stop thinking when they panic.  I used to manage a group of computer operators.  One day one of my employees collapsed.  I directed her coworker to call the emergency number while I was checking for breath and a heartbeat.<p>Since it was a military base with an obsolete phone system, the emergency number wasn&#x27;t 911, and even though there was a huge red sticker on the phone (which she&#x27;d used for years) with the emergency number, the coworker kept punching in 911 over and over, getting more and more panicked when it didn&#x27;t connect.  She froze up so badly even when I told her what to do she couldn&#x27;t do it - I had to take the phone from her and dial myself.<p>She would have been fine if 911 actually worked, though, because that&#x27;s the emergency number that had been drilled into her since childhood.<p>That job (because of that incident and another when the fire suppression system went off) taught me all those stupid-seeming standardized emergency systems really can save your life.  Even if you&#x27;re the sort of person who can keep your head in an emergency, you may need help from someone who can&#x27;t.