Activating functions during a call
The following functions are available during a call:
End call
Microphone off
Numerical keypad (show to send DTMF tones) 
Transfer to phone (an active call in hands-free mode is transferred over to the telephone)
Select a function.
Putting an active call on hold
Tap on the contact or the call.
The call will be put on hold.
The call on hold can be ended any time or re-activated by tapping again.