Is ATT blocking iPhone 3G on old (blue) network?

[dush2phone]

Hi,

I ran into an interesting problem with my 3G phone.

When I put in my old (blue) SIM using a Gevey adapter the phone
see the network fine. However, I'm unable to make outgoing calls and when I call the phone it rings once and then ends the call.

However, the same phone works with my regular 3G Sim both with and without the Gevey.

The phone also works fine on Tmobile using the Gevey adaptor.

Is ATT blocking out all iPhone IMEIs on the old blue network?

[boxxa]

I am not a 100% sure but isnt something different with the 3G SIM cards so you can not use them in a old device that is non 3G capable?

[XFaega]

Just make sure that the C-Phone that you are using is unlocked. I had problems with my new 3G iPhone and had to use my old iPhone. I did a complete erase and unlocked the old iPhone and worked fine.