ISP's that allow Indirect Access Numbers 6 January 2021 at 5:22PM in Phones & TV

Geoff_W

I am currently with Virgin Media and use 18185 for my landline calls. If I move away from VM I don't want to lose my 18185 access but it's very difficult to find out which ISP's allow Indirect Access Numbers to be used. I believe that BT and Plusnet allow them, but what about others such as Shell Energy et al? Is there a website which has a definitive list of ISP/Indirect Access status?