roListScreenEvent detect keypress

How might I determine when the Astrisk button has been pressed when a user is viewing an roListScreen? With the code snippet below I can tell that a button was pressed, but haven't found which function to call to determine which.

while (true)
msg = wait(500, port)
if (type(msg) = "roListScreenEvent") then
if (msg.isRemoteKeyPressed()) then
print "Remote Key Pressed"
end if
end if
end while

Thanks!