Carrier Bundles provide a way to organize all customizations related to carriers in one place. These include voice mail numbers, MMS and APN settings etc.
For users on carriers other than the Apple's official partners, carrier bundles allow to configure important settings such as APN and enable features like MMS and tethering.
On the iPhone side, carrier bundles are stored in the following directories:
- /var/mobile/Library/Carrier Bundles/ - bundles downloaded via iTunes.
- /System/Library/Carrier Bundles/ - bundles provided with the firmware image.
If two bundles with the same name exist in both paths, the one on user partition takes preference. This allows Apple to update carrier bundles without releasing a whole new OS.
Carrier bundles are ZIP archives with .ipcc extension. They contain the mandatory Payload folder that includes the bundle itself and the symlink:
\Payload\ \MyCarrier.bundle\ \carrier.plist - carrier settings go here \Default_CARRIER_MyCarrier.png - logo for light background \FSO_CARRIER_MyCarrier.png - logo for dark background \Info.plist - bundle description \12345 - symlink to MyCarrier.bundle (12345 is MCC+MNC)
Enabling .ipcc support in iTunes
By default, iTunes allows only carrier bundle updates from Apple. However, when the "carrier-testing" preference is enabled, .ipcc files can be loaded from the user's hard drive by clicking either "Check for Updates" or "Restore" button while holding Shift (on Windows) or Option key (on Mac).
To enable .ipcc support on Mac OS X:
1. Quit iTunes.
2. Open Terminal and paste the following command:
defaults write com.apple.itunes carrier-testing -bool true
To enable .ipcc support on Windows:
1. Quit iTunes.
2. Press Win-R and paste the following command:
"%ProgramFiles%\iTunes\iTunes.exe" /setPrefInt carrier-testing 1
Each APN in the carrier.plist has a numeric type-mask. It designates what the APN should be used for (eg. phone data, tethering, visual voicemail, MMS, or a combination). This table shows what each-type mask designates an APN for.
|2||Visual Voicemail (VVM)|
|3||VVM & Data|
|5||MMS & Data|
|6||MMS & VVM|
|7||MMS, VVM, Data|
|49||Tethering & Data|
|50||Tethering & VVM|
|51||Tethering, VVM, Data|
|52||Tethering & MMS|
|53||Tethering, MMS, Data|
|54||Tethering, MMS, VVM|
|55||Tethering, MMS, VVM, Data|
iPhone 3.1 Changes
As of iPhone OS 3.1b1, the carrier bundle APN settings are now signed to prevent tampering/modification.  Due to carriers around the world having set up APNs specified for specific purposes, such as tethering, this will stop users from modifying the carrier settings to bypass the specified APNs that may require payment for access. This is also a concern for users of carriers that do not officially offer MMS or Tethering services for users at all.