Nildram the UK ISP has set up a migration service for BT ISDN users to upgrade to wires-only ADSL.
The conversion process from Highway ISDN to Nildram Home, or Office, ADSL service costs £27.99, payable to BT. Basically you"re upgrading from 128kbps to an always-on 512Kbps connection
Here"s how it works, BT manages the conversion of a BT provided ISDN line to PSTN and subsequent activation of the customers" ADSL service. Should the conversion fail for technical reasons, the engineer converts the line back to the original service and all associated charges are cancelled.