I suppose this could work for any cell phone, really, but I never fully appreciated the need for it until my iPhone.
You know how you call a service that requires a boatload of button pushing, like checking your bank balance or phoning in a renewal for a prescription, and you’re left constantly pulling your phone up to your ear to see what’s being said, and then down in front of you so you can type the next number? If you ever make a mistake while typing and it starts talking to you, you won’t even hear it until you’re 8 numbers into your mistake and thoroughly confusing the thing.
Next time, put it on speaker phone.
Now you can keep it right in front of you while you type, and still hear what’s being said.
When you’re done with the typing, take it off speaker phone and talk to the human.