As standard (default setting), external diversion is restricted for all Groups. This can be changed in BT Quantum system programming.
As system administrator, follow the steps on page 65 & 66 (Group Diverts section) of the BT Quantum administrator's guide.
Take care - it's possible that external divert could be misused.
Once you have programmed the system, the external divert will need to be set up - see
How do I divert calls on BT Quantum?
Note: You will need
Adobe Reader to view PDF documents.