Siri / Voice Recognition not working (iPhone 5, iOS 6.1.3, O2 in UK)

Hi all,

Siri and any sort of voice recognition has not been working for me since yesterday.

I have disabled and re-enabled Siri, done a 'hard' reset, and have also Reset all Settings.

I get no response from Siri, and on a text message etc, 3 purple dots then nothing.

From a web search I cannot see any similar issues at present in terms of network/server issues.

Any ideas? Problem with the rear mic maybe?

Thanks,
Greg