In addition to other features (including push email and turn-by-turn navigation), this new operating system introduced the App Store—Apple's new distribution platform for third-party applications.

In 2008, Import Genius, a provider of business intelligence for the import-export industry, used electronic customs clearance data, which is published by U.S. Customs and Border Protection pursuant to the Freedom of Information Act, to detect the arrival of the iPhone 3G prior to Apple's announcement.

[17][18] The iPhone 3G came preloaded with the latest version of iOS and continued to receive updates to its software for over two years, with major iterations released on an annual basis.

However, it does provide access to a unified mailbox feature, home screen folders to better organize apps, playlist creation, and other enhancements.

This update was widely criticized for slow performance on iPhone 3G, though September 2010's iOS 4.1 release resolved this problem.

However, unlike more modern iOS devices, this update again does not provide iPhone 3G owners with access to important features, in this case, the Game Center application.

The iPhone 3G introduced the first official color options for the outer casing, with the 16 GB version available in black and white.

A 3-axis accelerometer was included to sense the orientation of the phone and change the screen accordingly, allowing the user to easily switch between portrait and landscape mode.

These enhancements allow faster data downloads and turn-by-turn navigation with maps compared to previous devices.

[23] Shortly after its release, the iPhone 3G faced criticism for frequent dropped calls and sluggish web browsing experiences.

This update presumably addressed the problematic chip's behavior, improving call quality and internet connection speeds for iPhone 3G users.

While user reports indicated connectivity issues, AT&T, the primary carrier for the iPhone 3G at the time, offered a contrasting perspective.

An article in the Wall Street Journal's Digits column on July 28, 2010, reported that iPhone 3G phones updating to iOS 4 responded slowly, had diminished battery life, and became excessively hot.