Screen Saver when calling and need to use the Keypad, the screen saver doesn't detect the phone has left the ear and blanks out the screen. Even ending a call is difficult as the screen blanks out within seconds

Question

I have to use the Keypad a lot when making calls.  Make the call, the Robot then asks to enter a number for a service, pull the phone down from the ear, the screen may light up for a second, but then the screen saver cuts in, blanking the screen out.  Sometimes you hit the Home Key to awaken the sccreen, enter your number and then back to the ear to hear the next set of instructions.  Back and forth just trying to enter the options is a pain.  Sometimes even trying to end the call, the screen blanks out and you fight to try and end a call.
If I use the Speaker function the keypad works; the speakler phone is not alway appropriate. 
It appears that the phone gyro, doesn't detect the phone has moved from the ear to the viewing angle.  This wasn't an issue until recently and I can't remeber if it's the iPhone 5 or one of the updates.  It definitly wasn't there earlier on, as I threw away an Windows 6.5 phone for the same problem. 
I'm not sure if it's a hardware or software (design) issue.

Answer 1

It is not the gyro. This has everything to do with the iPhone's prioximity sensor.
Are you using a case that may be blocking or partially blocking the proximity sensor? If you are using the case, remove the case prior to the next call to see if the same occurs without the case.