Call waiting
Rejecting a Knocking Caller (on an Analogue internal phone) 
R > 0
R
Flash key or Query key
*Further help under Call waiting
Accepting a Knocking Caller and Disconnecting the Active Call (on an Analogue internal phone) 
R > 1
R
Flash key or Query key
*Further help under Call waiting
Accepting a Knocking Caller and Putting the Active Call on Hold (on an Analogue internal phone) 
R > 2
R
Flash key or Query key
*Further help under Call waiting