AAISP could become a Nominet-accredited ENUM registrar, allowing customers to pay a small fee and register their phones in the real UK ENUM. http://www.nominet.org.uk/enum/registrars/becomeregistrar/
Advantages: Provide a useful service (nobody else seems to be actually doing this yet) whilst bringing in some revenue.
Last time I looked, there were about 3 registrars in the UK - none of them were active and all were overpriced. Hardly conducive to ENUM takeup in the UK!