SIS file in v2.2.8 is usually customised to the provider; there´s another one at http://download.vodafone.de (in German, click on the link where it says user: connect and pw: connect. SIS file is considerably larger than usual (> 1MB) but it works.
I´m using a plain vanilla P910i of the first generation issued by Vodafone Germany (unbranded Symbian surface), stepping 162006 R2A17. It works !

Which file do you mean at vidafone.de ?

The Sony site link does not point to a sis/zip file... please specifcy which file is to be downloaded or send direct to me at simonm68@yahoo.co.uk thanks

i have everything you state up and running - EXCEPT vodafone - they refuse to set up blackberry using the imei and pin i get from my p910i. same old reason - legal issues with rim

how did you go about adding bb settings to your account?

The IEMI / Pin setup worked without having to contact Vodafone, just went to mobileemail.vodafone.net and entered the details (this also works for Nokia 6810's and 6820's).
Getting Blackberry on your tariff can be harder. For me I just borrowed somebodys Blackberry SIM card to test the software. Best method is to say you've been given a Blackberry 7100v from work and you'd like to try it on your current talk plan. It should cost about £15+vat per month.