The BT call screening phones get very mixed results on here when connected to a VM line.
Once the line gets switched over from a conventional socket to the back of the VM hub, there have been lots of reports on here that the call screening functions seem to stop working reliably (some mention all calls coming through unchecked, many mention 'withheld' calls no longer being screened).
There are also issues reported with the BT phones showing the incorrect time when they synchronise to VM caller ID (which. for some reason best known to VM, seems to be synchronised to an American time server).
https://community.virginmedia.com/t5/Home-Phone/Wrong-Time-on-Handset-since-moving-to-Digital-Voice/td-p/5287304
For call screening I have used this device in the past very successfully on a conventional VM landline
https://www.truecall.co.uk/category-s/116.htm
which is the full standalone unit for trueCall (present as a 'lite' version in the BT phones)
At £109.99 it is an expensive device but past topics on here have highlighted that trueCall support can dial-in to the unit remotely and reconfigure it to match VM line conditions and caller ID (whereas the BT phones cannot be reconfigured).
A generic phone which only stores and blocks individual numbers (rather than screens out calls) is no use really against the scammers as the fake caller ID numbers change regularly and it is a never-ending task to keep adding blocked numbers. The fake caller ID numbers are changed regularly so, even when a blocked number is stored in a phone, the chances are the number will never be re-used/blocked in the future.