It is available in settings menu of different phone morever you can call on a number provided by service provider to divert calls.
Anyways you can try below numbers as per requirements.
Call diversion when busy:
**67*number#
Divert to the given number
#67#
deactivate call diversion
##67#
Erase call diversion
*#67#
Request status for call diversion
Call diversion in case the handset is turned off or has not coverage:
**62*number#
Divert to the given number
#62#
deactivate call diversion
##62#
Erase call diversion
*#62#
Request status for call diversion
Call diversion for not responding
**61*number**x#
Divert to the given number aber x seconds (x=5,10,15,20,25,30)
#61#
Deactivate call diversion
##61#
Erase call diversion
*#61#
Request status of call diversion
Call diversion for all conditions above:
*#004*number#
Divert to the given number
#004#
Deactivate call diversion
##004#
Erase call diversion
*#004#
Request status for call diversion
Always divert:
*#21*number#
Always divert to given number
#21#
Deactivate call diversion
##21#
Erase call diversion
*#21#
Request status for call diversion
Erase all call diversions:
##002#[dial]
Remove all call diversions