ugh, i'm in this boat too. i had it for awhile too and then it mysteriously disappeared...hmm? i've tried the cydia apn editing hack - nope. tried resetting networking settings - nope. i know it's not my sim card because i'm using t-mobile usa and also since it was there before.

any more thoughts??

I think i lost my "Cellular Network Settings" messing with the various t-mobile carrier packs from Cydia.

I tried both fixes. the "APN Editing" app from Cydia and resetting network settings. neither worked. (that's when I found this thread)

Getting desperate I then uninstalled "APN Editing", and installed a profile from help.benm.at, still no settings.

Finally I remembered i still had one of the carrier packs installed, I removed it via Cydia, and rebooted. still nothing, but then I did the "network settings reset" and it was back!

Im not sure if the profile thing helped at all, but those are the steps I did which worked for me, I hope this helps you all out!

go to Unlockit - APN Changer for your iPhone
it works for me
the problem that i have now is i can't recieve calls
any help
thanks