It sounds like what you are saying is you will be advertising 2 /19s plus advertising a /18 that you won't be registering just to get the traffic to come out of Sprint.
You can certainly register a /18 and the whole world would much rather you advertised just the /18 and and not the /19s.
This sounds to me like some people don't know or care who the other /19 belongs to and are just announcing the /18 for Sprint's sake. The two /19s would be announced regardless of anything ANS does or regardless of any registry issues. Is this the case?
See my later mail. Of course it would be irresponsible to do this without consent of the owner of the upper half of the /18, however most (all that I've seen) of the /19s RIPE are currently assigning from 195 have been lower /19s with the upper half not used, so they can grow. Please don't take what I wrote as a criticism of ANS - I've never had any problem with ANS filtering as it's entirely predictable and worked precisely in parallel with the registries, and the ANS NOC is admirably helpful in sorting out any filtering problems. I was describing a marginally unpleasant workaround to an otherwise intractable (sp?) problem (RIPE and Sprint not agreeing on minimum block size) - and AFAIK the only way to get /19s routed to Sprint when the other half isn't in use in many cases (yes, I know about proxy aggregation etc.). I'd be the first to say it isn't nice, but fortunately it's now (or will soon be) unnecessary. My point was the fact RIPE and Sprint *didn't* agree would actually encourage hacks like this and in some cases increase the number of routes carried. Alex Bligh Xara Networks