There are two buttons on the underside of the livebox and there is a sequence they need to be pressed in so you can 'pair' the wireless network, only when it's in pair mode can you actually make the first connection
It's a kind of MAC filtering.
A search on google should sort it out for you
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here is a video guide from oranges website
http://www.orange.co.uk/time/livebox/setup_9.htm