You can answer a call when you have another call in progress.
To activate call waiting (network service), select Menu > Settings and Calling > Call > Call waiting.
To answer the waiting call, press the call key. The first call is put on hold.
To switch between the two calls, select Options > Swap.
To connect a call on hold with an active call, and to disconnect yourself from the calls, select Options > Transfer.
To end the active call, press the end key.
To end both calls, select Options > End all calls.