I posted this to another thread a couple of days ago:
It really isn't possible to be just one operator. Orange (under it's own brand) for example doesn't operate in countries like Finland, Sweden, Norway, Denmark, Iceland, Belgium, Bulgaria, Czech Republic, Estonia, Germany, Greece, Latvia, Slovenia... And the list is just as long for Vodafone.
So it's really not possible to do in Europe.
It really isn't possible to be just one operator. Orange (under it's own brand) for example doesn't operate in countries like Finland, Sweden, Norway, Denmark, Iceland, Belgium, Bulgaria, Czech Republic, Estonia, Germany, Greece, Latvia, Slovenia... And the list is just as long for Vodafone.
So it's really not possible to do in Europe.