To Answer a call just press the call button or the <Enter> key.
If there are other incoming calls these are placed in a Queue sorted by incoming order, you can monitor and manage them by the Activity Panel, selecting a call and pressing the call button, the <return>key or double clicking it to answer.
If you have an active call in progress, this will be placed automatically in Hold.

In the Activity Panel:

• the non answered calls are marked in green,
• the hold calls are marked in yellow,
• the selected call is marked with a white arrow
• The ANSWERED call will be green,

while NOT answered will blink from green to red.