Basic specs for Siemens S46
Technology-- GSM / D-AMPS
Band / mode-- GSM 900/1900 / D-AMPS 800/1900
This answers the question about why this phone won't work. Virgin is a 1800 band network and the specs above do not list this band as one of those on the phone.
it is also worth noting that while European networks do not charge for incoming calls (other than roaming) it does cost people somewhat more to call you.