How do I get the dial pad back after the screen times out, Galaxy S4?

[AC Question]

How do I get the dial pad back after the screen times out? Galaxy S4

While I'm talking on the phone with the dial pad displayed, the screen times out and goes blank. Today I tried to get the dial pad back so I could answer a survey and would up hanging up instead.

What button or buttons should I press to recover my dial pad without terminating the active call?

Thanks!