iOS 6 activation error on iPhone 3GS without SIM card I recently got an iPhone 3GS without a SIM card. I upgraded it to iOS 6 from 5.1.1. 
However, the phone is stuck on "Activation error" after successfully connecting to my WiFi. The screen says:


  Activation request could not be completed. If the problem persists,
  please contact customer care.


If connected to iTunes 11, iTunes says:


  We're sorry, we are unable to continue with your activation at this
  time.


Resetting the phone doesn't work. Anybody has any ideas, besides contacting customer care?

Edit: The problem was solved by inserting a valid SIM card.
I had a similar error once, and if I remember correctly, it was that the time on the iPhone was wrong (months or years, I think). Setting the time correctly allowed it to go through.