Scenario;

Customer forwards their calls out to a mobile out of hours (managed by DDI pointed to virtual SLT in particular Ring Plan).
When mobile receives the forwarded call, main bearer of ISDN2 show as incoming CLI.

Objective;
Customer wants the originating CLI to be passed through.

What I have done so far;
I have enabled EFWD in MMC419
I have removed the leading 0 from the external forward destination in MMC102 on the virtual SLT in question.
I have contacted the line provider. In this case I believe this to be ultimately Gamma who have confirmed that the 'Call Deflection' feature is enabled.
I have removed all data in MMC323 (Send CLI Number)
I have turned 'Held Party CLI send' in MMC210/5.14.4


What am I missing here?

This is a Samsung 7030 on V4.53b.