vodafone and Orange UK share infrastructure (includes Three)
 

Orange and Vodafone are to share the same network infrastructures, as a way of saving Vodafone money and increasing network coverage for Orange, this maybe happening. But since they both use different frequencies, its sounds very expensive and disruptive to do.

Customer benefits:

Vodafone customers will benefit from vodafones great value call packages such as free weekends and get better network coverage with the help of Orange. Vodafones coverage doesn't seem that good anymore with calls cutting off saying network busy which is really annoying!

http://www.theregister.co.uk/2007/02...afone_network/

Same possibilty in France and Belgium? (SF network/Vodafone Belgium and Orange France/Belgium)

Hutchison 3G UK (3-Mobile UK) now use Orange
 

3 customers who fall out of the 3G coverage area will now use the Orange network. Hutchison 3G has appointed Orange for national roaming partner.

Pre-December customers will automatically fall onto the O2 network but will have a choice of using Orange. New customers will automatically fall onto Orange. This is because Hutchison 3G is phasing out O2.

Quite a good idea!