When you receive and incoming call on your phone, you can choose to answer it in various ways.
Options
Pick up the handset.
Press the Speakerphone key.
Press the Headset key
Tap the Answer button
Answering a Call When in a Call
You can answer the incoming call when you are in an active call.
Tap the Answer button on the touch screen.
The active call is placed on hold and the incoming call becomes active.