iPhone Upgrade for iMessage, Then Downgrade?

[klamse25]

I have an iPhone running 5.1.1
I only want iOS 6 so I can add my phone number to iMessage (For my Mac and iPad)
If I upgrade to iOS 6 temporarily, add the mobile number, then downgrade, could I keep the number intact?
Maybe a silly question.

 

[klamse25]

Just tried it.
After I upgraded to iOS 6, then downgraded, it went back to using my email for iMessages.
Oh well.

 

[dhlizard]

And you seem surprised.
Firmware doesn't work that way.