When active, your phone will notify if you receive a call while you are already on another call, allowing you to put one on hold and answer the second call.
If you don't answer a call, it we be diverted to a phone number you can set here
Check Status: *#61**#
Deactivate: ##61**#
Activate: **61*<Phone Number target>#
When active this will divert calls if your phone is off, you don't network connection or are otherwise unreachable.
Check Status: *#62**#
Deactivate: ##62**#
Activate: **62*<Phone Number target>#