Unless you have the phone setup to end calls with the power button, pressing the power button will turn the screen back for you to access the keypad.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Right now, I HAVE to have the phone set up that way or I have to wait for either A) the other party to hang up first or b) until the 'system cannot process my request'. But I cannot use the type pad during a phone call and will not turn back on when I press the power button, so this is really frustrating as my VM is adding up and I can't type in PW.