You are on the phone and you enter an elevator. Instead of saying... Hey I'm in an elevator I'll call you back in a second. You decide to talk louder and think your cell can get coverage inside a metal box going up or down a few stories.
Then you are shocked that it doesn't work and the call hangs up. Just hang up and call them back or finish the conversation and then go up or down.
I do not know of any cell phones that allows you to continue talking and be traveling in an elevator. If you do then I can tell the people I see that suffer from no coverage in there to help them out.