To change your iPhone Carrier logo is possible.
To change your carrier logo, the directories you’ll need to know are /System/Library/Carrier Bundles/ and Themes/themename/Bundles/. The first one is the directory where all the bundles containing pictures and other data for the different available carriers are located. The second directory is where you must put the directory corresponding to the carrier you’d like to change. For example, /Bundles/com.apple.ATT_US/ is where aT&T modifications go. Just like for applications, you’ll need to find the Info.plist in the bundle to see what to name …