iphone 4 ultrasn0w no cell data network

iphone 4, 4.01, jailbroken & ultrasn0w - bought with AT&T and am trying to use in Luxembourg with orange.lu, my local provider. Everything else works, but I can only access cellular data about 10% of the time. Sometimes works, sometimes does not. Phone shows 3g connection all the time, but I keep getting the message 'could not activate cellular data network'. Very frustrating. Orange.lu have told me this is because the phone is jailbroken. I have also tried the APN setting route using the site in New Zealand, but to no avail. Any suggestions here?

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Originally Posted by ganschman

[...]I can only access cellular data about 10% of the time. Sometimes works, sometimes does not. Phone shows 3g connection all the time, but I keep getting the message 'could not activate cellular data network'. Very frustrating.[...]

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Yep. 4.1 too. Very annoying!

Your SIM card is too thick. That means you are tethered wrt iPhone SIM tray eject tool[tm]. You have to carry it everywhere and keep ejecting and inserting back the SIM until it wears out and becomes slim enough to allow cellular data network to pass through.

Of course, that was a joke. Cellular data is really unstable with the latest ultrasn0w (that is, 1.1-1). Google does not know of any fix, apart from that stupid eject/reinsert trick -- which may or may not work.