Alcatel Temporis IP150 Manual page 42

F5 has to be configured for this function as well if all
programmable keys are needed. If F5 has any other
function, then only F1 to F10 will be available.
When F5/F15 are configured to "Access F11-F20",
the meaning of the led will be as follows:
Orange: F11-F20 are active. If user presses the key
on the left topmost position, F11 wil be triggered
Off: F1-F10 are active. If user presses the key on the
left topmost position, F1 wil be triggered
Temporis IP150 Administration and Provisioning Guide ed 0.1 42/106