User Follow Me
From Taridium
Follow Me is similar to call forwarding, but allows you to specify multiple numbers that can be rung in sequence or all simultaneously.
Optionally you can have your default extension ring along with your forwarded call or use the follow me feature in conjunction with your call forwarding settings.
Checking the only forward if caller ID is in favorites will cause the call forwarding only to kick in if the caller ID is in your favorites list.
Note that the total number of seconds that all extensions will ring in Follow Me must be less than the number of seconds specified for Voicemail delay plus any call forwarding delay.
Checking the only forward if call was attempted X times within the last Y minutes will cause the the call forwarding only to kick in if the same caller with a valid caller ID has attempted calling this extension X times within the last Y minutes. The default settings for X is 3 attempts and Y is 10 minutes.