In reply to a post by MHC:

How do you get the BT Digital Voice service onto a Gigaset base?

By connecting the base station directly to the ATA port on the Smart Hub 2. That gives full functionality of the base station.

Gigaset Dect handsets can be paired directly to the SH2 but that breaks many of the Gigaset features including the contacts directory.

Indeed. Analogue used for home and voip used for business.

So the DV service is not managed by the Gigaset base, just the analogue presentation.