The "conference call" option only works if YOU are the one in the middle, so to speak, and initiating the calls to each party. If you are RECEIVING a call, you cannot initiate a conference with someone else from that call.

You would call person #1, then flash and call person #2, then flash again and all three of you are connected.

To conference with an INCOMING call, the person calling YOU would have to initiate the three way calling.

I hope that makes sense....