I don't mean to offend anyone, but some phone calls are just plain boring, and being put on hold is shittier than eating three-day old sushi.
If you're on hold or trying not to fall asleep during a talk with grandma, you can multitask by playing a game or texting someone more interesting. But when you need to take the phone of speaker mode, it's no quick task to do so when you're messing around outside the dialer.
To avoid having to put the other person on hold while you get your shit together, use Blimps - Floating Dialer (free on Google Play) by Android devs Curly Y. This app will give you... more