Answer
Before making changes, print out what you have in case you make a mistake

Remote Call Forward allows your Call Forward All Calls feature to be activated from another phone.  You should study the feature in the Feature Guide or here.

In summary, you will need to define:

• LD 15 FFC_DATA: Station Control Password length
• LD 57 FFC: Remote Call Forward Activate/Deactivate Codes
• LD 10 / LD 11: SCPW (Station Control Password)
• Then use this "RCF Code Wallet Card Generator"

To activate from outside the PBX, you will need to define DISA.

Link to this page: http://www.ghtrout.net/rdr/rcf.html