Ericsson 4422 - Manual (Page 48)

Call Forwarding
BusinessPhone – Ericsson Dialog 4422 IP Office 48
Re-activate External Diversion
Divert your calls to an external diversion address. *22*#
Press to activate the programmed External Diversion.
Verification tone. You can make outgoing calls as usual. A special
dial tone and the display indication reminds you that call forwarding
is active. í
Press to finish the procedure.