Hook flash for call waiting

[sadale_1270]

I just configured a W52P for my home phone network. I have a primary phone number that is a POTS line with a Digium FXO card connected to my asterisk server through dahdi. I also have a couple SIP registrations to external services.

When I get a second call on my SIP trunks, the handset gives me a call waiting tone and I can accept the second call. When I get a second call on my POTS line, I hear the tone, but because that second call isn't handled by asterisk itself the handset never gives me the opportunity to hook flash to answer it.

What I am looking to do is program one of the soft keys to be a hook flash, or perhaps program the "R" key to be a hook flash rather than a transfer, so that I can answer call waiting on my handsets. Can you help me learn how to do that? Can these keys even be programmed?

Thanks!