I occasionally hear a chirp when I'm on a call, which I believe is a call waiting alert. However, my handset's flash button doesn't transfer me to the call. I don't have voice mail because I'm using the unlimited local calling tier. However that tier does include the call waiting and caller ID features. Therefore, I should be able to use my call waiting feature. The flash time for the flash button is set to the default 700ms, but there are 12 settings from 80 ms to 900 ms. What is Comcast's recommended flash time for best reliability of a flash button on a handset? At least if I know I'm using the optimal setting, I can rule out that as the reason why I can't connect to the second incoming call.