Heres a couple of links which customers of the above companies might find usefull. Allows you to use different network at no extra cost . I believe it is only 2g at the moment but 3g is coming soon apparently.
https://kareena.orange.co.uk/share
http://www.t-mobile.co.uk/share/
I know this isnt x10 specific so feel free to move it if required!
https://kareena.orange.co.uk/share
http://www.t-mobile.co.uk/share/
I know this isnt x10 specific so feel free to move it if required!