iPhone users began to receive AT&T carrier settings updates on February 7 in iTunes after clicking the “Check For Update” icon. After extracting the .ipcc file, two new carrier images were found, both for AT&T’s upcoming 3G MicroCell network that allows users of any 3G enabled phone to use a purchasable mini “cell tower”, known as a femtocell, to boost the signal in their home.
Carrier updates are described in this Apple Knowledge Base http://support.apple.com/kb/HT1970
iTunes 7.7 and later has the ability to update the carrier specific settings on iPhone with iPhone 2.0 software or later. Carrier settings updates are small files (about 10k) that are downloaded from iTunes to be installed on your iPhone. The carrier settings can include updates to the default APN (how iPhone accesses the carrier’s cellular data network), special dialing codes at Settings > Phone > [Carrier] Services, default settings for Stocks, Maps, Weather, and other items.
The femtocell attaches to your router and transfers 3G voice and data through the internet. It allows for 5 simultaneous phones to be used with the device; while competing femtocells from Verizon and Sprint only allow 4. The device is securable, so only cell phones that you authorize can use it. There is a monthly service charge as well as the initial cost and Cisco is known to be manufacturing these femtocells. This service is currently being tested and will be availiable in the second quarter of 2009.