Geo sells same network to both Carphone and Tiscali.

It looks as if both Tiscali and Carphone Warehouse have bought an identical dark fibre backbone for the UK from Geo. Obviously, when lit this fibre adds plenty of capacity to both networks and more importantly provides plenty of PoPs for interconnection with their unbundled exchanges and presumably will involve a drastic reduction in backhaul costs.

Geo was originally built alongside old British Gas pipes and was called 186k, before being sold to Hutchison Whampoa and renamed Geo. They have an even more interesting London Metropolitian Network which is built in the sewers of Thames Water. Carphone have leased fibre in these sewers to connect up their core sites in the capital.