Forward calls on Optus mobile
Dial codes with a ring time you choose, and how to remove them.
All calls, without ringing: **21*NUMBER#: ##21#
No answer: **61*NUMBER**RINGTIME#: ##61#
Busy: **67*NUMBER#: ##67#
No coverage: **62*NUMBER#: ##62#
Cost
Test it
Optus: manage call diversions (official page)