1. Find out the MCC/MNC of your simcard
2. Connect via SFTP to /System/Library/Carrier Bundles/ on your iPhone
3. Duplikate ATT_US.bundle on the iPhone
4. Rename to your needs e.g. my_Vodafone_GR.bundle
5. Doubleclick to open the renamed bundle
6. Delete everythimng inside exept "version.plist"
7. Open a webbrowser on your PC (MAC or WIN) and goto http://www.volkspost.de/plister/
8. Enter the name of your bundle e.g. my_Vodafone_GR
9. Hit "Print Info.plist to screen" or "Download Info.plist to PC"
10. When hitting "Print Info.plist to screen" save the new page as "Info.plist" to your PC
11. When hitting "Download Info.plist to PC" its downloaded as my_Info.plist, delete my_ in the filename
12. Enter all the Information for creating the carrier.plist.
13. Hit "Print carrier.plist to screen" or "Download carrier.plist to PC"
14. Same steps as 10 & 11, resulting file is carrier.plist
15. Copy both files via SFTP inside your new bundle and quit your SFTP programm
16. Open a Terminal SSH connection as root to the iPhone
17. Move to the location where to create the symlink(s) with
cd /System/Library/Carrier\ Bundles/
The folder "Carrier Bundles" ahs a space in between, on a Mac it has to be commented out as seen above. Give it a try under Windows.
18. Create the symlink with (example)
ln -s my_Vodafone_GR.bundle 26207
replacing my_Vodafone_GR with the name of your bundle and 26207 with your sim's MCC/MNC
19: Making all that work do the SIM card switch routine. Reboot after reloading the new SIM. Only then, the symlink is accepted and working.
20. Install Erica sadun's "Make it Mine" to type your carriers logo the way you want and "Boss Prefs" to be able shutting down/switch on EDGE. Both are on Installer.