Jim wrote:

For example in the UK context, it's not (yet) possible to register premium-rate and free phone numbers under 4.4.e164.arpa because authenticating them is too hard.

Authenticating free-phone and premium rate numbers is not harder then authenticating any other number. Freephone numbers in ENUM are not a problem at all, beside the fact Telcos do not like the idea. It is ideal for the customers = call centers migrating to VoIP anyway. In Austria freephone numbers are allowed in ENUM and the US enum-forum is also going this way. Another issue is premium rate numbers: since a customer must be crazy providing an ENUM entry with no termination charge there is no need and business case. Regards Richard