"Waiting" means that you will be notified on your Samsung Galaxy S6 know when during a telephone call another call. This function is very useful, since you so then can decide whether to terminate the current call and answers the new call, or whether manauf this is not responding.
The function call waiting is provided by your mobile service provider or the mobile network. Unfortunately, some providers do not offer the call waiting option.
If the "Call waiting" with you not be enabled, then you can this with your Samsung Galaxy S6 as follows to unlock:
Opens to First, the Phone app, tapping into these top-right of "More". Navigate then in the next step on "More Settings". The settings are then retrieved and then lists from your mobile operator. Here you can see now equal to the "call waiting". By means of the controller you can now activate this option. Finished!
Immediately the call waiting service will be active and to inform you during a telephone conversation and a new call to your Samsung Galaxy S6.