You bought your iPhone before 2008 and are still using it? If so, I'm impressed. Otherwise, Apple has been clear since the very beginning of the App Store that

You bought your iPhone before 2008 and are still using it? If so, I'm impressed. Otherwise, Apple has been clear since the very beginning of the App Store that third-party apps require approval and can only be installed via the App Store. Why did you believe otherwise? Third party iPhone and iPod touch applications must be approved by Apple and will be available exclusively through the App Store. https://www.apple.com/newsroom/2008/03/06Apple-Announces-iPhone-2-0-Software-Beta/ https://www.apple.com/newsroom/2008/03/06Apple-Announces-iPh...