Just FYI, I encountered the following with another user, on T-Mobile.

This person is using a 9700 without a data plan and happily using wifi. As many or most know, T-Mobile is known to allow wifi without a data plan.

So, this user upgraded to a new version of OS6 in place of the OS6 version he was running. Wifi no longer worked. Both OS versions were official T-Mobile releases, and 9700 was T-Mobile Brand.

T-Mobile rep on the board thought something was wrong, expecting that wifi would work. The user downgraded, wifi works; upgrade again, no wifi.

I got my old 9700 and verified that wifi still worked with no SIM. Upgraded to latest T-Mobile OS 6. No wifi. I checked, the service books were there. Hmmm. Put in my SIM, wifi works. Take out the SIM, no wifi.

All the above posted on the T-Mobile forum. The T-Mobile rep later posts that after checking he has to report that a data plan is required with that OS.

So, there is more going on than service books. You apparently do need them, but they can be there and you still have wifi blocked.

Just sharing something I learned the other day. New to me anyway.