Select Edit Customer Details from the menu and the following line is at the foot of the dialog:
If you activate this feature, most incoming calls will be diverted to the emergency redirection number. If the premises are not accessible for any reason, this allows you to redirect calls to an external number.
Calling numbers in the call filter that have Do not divert set will not be redirected to the emergency redirection number.
The PIN number is for access from the non-DDI DTMF Menu. The menu allows you to activate and deactivate the facility through a menu. You can also activate and deactivate the facility via the menu above – this just allows one to activate the facility by dialling a number and using a menu.
When the key is selected from the DTMF menu, the caller is asked to enter the 4-digit PIN. Only if the correct PIN is entered, is the facility turned on or off.