Ok, so I work at a call center, right? People call us and we help them book travel. The call comes in and a template pops up on our screen with various bits of info such as the callers name and which company they work for. Do you have the mental image?
First we verify the name and then we ask them for a phone number that we can call them at if we become disconnected. It's good to have that number but it's usually not the question that the caller expects. This is especially true if they are having an emergency or are distracted or something like that. Sometimes they start to give you a phone number, realize that it's the wrong one and then as fast as possible give you the correct one.
That means that you have to quickly backspace so many characters and then ten key your butt off to get the right number in the template. Not so easy. In fact, if you wanted to make certain someone couldn't call you back this would be the best way to do so. (Except flat refusing to give a number. Or giving a number but lying about it. Or throwing away your phone.)
It's human nature, I think. They want to correct a mistake without taking up too much time. I get that. But...c'mon people! Work with us.