I think as far as number portability is concerned, the advantage can also be to the contract user.
Think about it.... new contracts used to be much more atractive than a upgrade/renewal of your existing contract. But very few people would take out a new contract after your two y expired becuase then your number have to change.
Now your number can stay the same even if you take your contract to another provider. Thus contract upgrades will have to become more atractive.
