At a guess if you press 9 you get transferred to a "real" operator who then tries to sell you something - which will be where they make their money.
I don't know about the technical side of what "might" be possible other than that but the premium rate side of the rumour is *DEFINATELY* a myth.
See these links for details:
http://www.icstis.org.uk/icstis2002/default.asp?node=-1 (the "£2 0 PER MINUTE AND £50 PER MINUTE TELEPHONE 'SCAMS' - URBAN MYTHS" heading part way down the page)
http://www.theregister.co.uk/2004/12...is_phone_hoax/
If ICSTIS say it isn't true they are the ones who should know!