Hi McFly,
For an unconditional call forwarding, this is *21# to turn it on and #21# to turn it off. You have to dial **21*(destination number)# to program the number you want your calls forwarded to.
For a conditional call forwarding:
Call forward busy: *67# to turn it on, #67# to turn it off. To program the number, this is **67*(destination number)#
Call forward no reply: *61# to turn it on, #61# to turn it off. To program the number, this is **61*(destination number)#
Call forward not reachable (device turned off): *62# to turn it on, #62# to turn it off. To program the number, this is **62*(destination number)#
Thank you!