What industry sectors are ripe for disruption?

Mobile Telecoms companies still like to play the haggling game of having you sign up to a contract, come to renew it, mention a friend gets theirs cheaper, say you'll go to a different provider, then finally get a rate you're happy with.
This process went by the wayside for most products years ago (can you imagine having a similar call with your landline provider)? Surely all those sales-people involved in this process cost the company money. So all it would take is for people to share information about what contracts they were on for everyone to become aware, adjust, and force the companies to accept certain uniform rates, focussing their efforts to attract users instead on levels of support, coverage and additional services.