Really? Have you actually TRIED to do this with the English UK version of Siri? /me waits for the "OPPPPSSS, I only looked at the English US version of Siri?"
Siri is available on iPhone 4s or later, iPad with Retina display, iPad mini, and iPod touch (5th generation) and requires Internet access. Siri may not be available in all languages or in all areas, and features may vary by area. Cellular data charges may apply. New female and male voices will be available initially in U.S. English, French, and German. Returning calls and playing voicemail are available on iPhone 4s or later.