From Snom User Wiki
- F_REDIRECT can be used to create a shortcut for setting up call forwarding for the phone. If you are using a programmable function key with LED, the LED will indicate the current state of the call forwarding.
- You have set F_REDIRECT:490 to one of the programmable function keys. Pressing that key will set up call forwarding of all or specified (on busy, after timeout) incoming calls to extension 490, as indicated by the lit LED. Press the key again to end call forwarding; the LED will go out. Similar mappings to other extensions can be made in parallel on other function keys. If you are using F_REDIRECT without a number the currently set number will be used for redirection. See also 'Advanced Functions'/'Call Forwarding'.