[muppetman11]

Originally Posted by 1andrew1

The three networks have argued that opening up their networks to rivals will increase costs, hinder investment and reduce quality.
Hinder investment - new regulations could reduce the return on existing investments and therefore deter future investments.
Reduce quality - multiple operators tampering with equipment will increase faults.
http://www.ft.com/cms/s/0/d03235aa-d...#axzz3VntuBCj0

Some of the arguments for opening the network can be found here and here