Use call waiting
When you have an ongoing call, the new call is signalled by a sound.
Press Connect.
Press Connect.
Swap calls
Your calls are displayed on a list and the call on hold is indicated by On Hold.
Press Swap to swap calls.
End active call
Make sure the call you want to end is active.
Press Disconnect.
Press Disconnect.
Press the Menu key.
Press Resume to resume the call on hold.
Exit
Press Disconnect to return to standby mode.