Avaya T3 (IP) Comfort - Manual (Page 94)

Assigning functions/phone numbers to keys
94
Customizing the telephone
Assigning lines to keys
Press the "Menu" function key.
Scroll to the Settings menu item.
Confirm your selection.
Scroll to the Function keys menu item.
Confirm your selection. The description and current assignment of all keys will
be displayed.
Scroll to the function key you want to change or assign.
Confirm your key selection.
Select the line you want to assign to the function key, e.g. Line 2.
Confirm your selection. You can now seize line 2 with this key.