most networks have either a 6/9/12 month downward migration policy, i think orange is 6 month, but dont hold me to that. You can buy out early, but you literally have to buy out; pay the remaining line rental, and sometimes a cancellation fee.
T-Mobile, dispite having the flexibility of Flext, only has an 11/17 month downward migration, depending on if it is a 12/18 month contract. Three, on the other hand, has brought out a £25 or 6 month extension to contract clause to downward migration...
I work in a high street multi-network retailer, so have access to all networks; three has dropped in our popularity immensely after this happened!
having said that, many of the stores i work for will offer a cash assist to buy you out; usually around £50 - £80. Not a massive help, but better than nothing!
Pete