iPhone Activating a UK Iphone to use with Straight talk service!

[cap2587]

I have a UK Iphone 4 that I would like to use on straight talk network. I am unable to activate this Iphone using an AT&T or straight talk SIM. How can I get past the activation and is it even possible. Would appreciate any input you can give me.

 

[dhlizard]

The phone has to be unlocked for use on AT&T or AT&T MVNO (Straight Talk)

 

[cap2587]

I was able to hactivate the Iphone using RedSnow. It is now running 5.1.1 firmware and has Cydia Installed. However, it is saying no service when I put my straight talk SIM in the phone. I am getting this Iphone ready for a friend and testing it out with my straight talk SIM to see if it works. When the SIM is in it is saying Unknown(in settings, phone) for the number and carrier. Let me know if you have any other ideas. Thanks

 

[dhlizard]

I was able to hactivate the Iphone using RedSnow. It is now running 5.1.1 firmware and has Cydia Installed. However, it is saying no service when I put my straight talk SIM in the phone. I am getting this Iphone ready for a friend and testing it out with my straight talk SIM to see if it works. When the SIM is in it is saying Unknown(in settings, phone) for the number and carrier. Let me know if you have any other ideas. Thanks

I thought I already answered the question.
You need to get a carrier IMEI unlock (or take your chances with a grey market dealer)