The two day period has nothing to do with the actual technology. I saw a friend of mine change his cell phone to have the same number as his home phone, and then back again, in a matter of minutes. This was a few years ago, maybe as many as 5.

The problem here is 100% beauracratic BS

£26m saving for us? sounds bloody unlikely.
A £26m saving over 10 years with 20 odd million phone users doesn't sound like we have a huge windfall coming our way any time soon.

I think 2 days is fair enough, now OFCOM how about focusing on real issues like rip off roaming, poor quality of customer service, misleading signal coverage maps...

Or are they too difficult?