iPhone 2.1 contains the following updates as listed by Apple:
- decrease in call set-up failures andcall drops
- significantly improve battery life for most users
- dramatically reduced time to backup to iTunes
- improve email reliability, notable fetching email from POP and Exchange accounts
- faster installation of 3rd party applications
- fixed bugs causing hangs and crashes if you have lots of 3rd party applications
- improved performance of text messaging
- faster loading and searching of contacts
- improved accuracy of the 3G signal strength display
- repeat alert up to two additional times for incoming text messages
- option to wipe data after ten failed passcode attempts
- Genius playlist creation

iPhone 2.1にすることで、使用できなくなるかと思われていたNetShareは問題なく動作した。さらに、日本語入力の処理能力が向上じ、連文節変換に対応。さらに、電波受信状況も良く、アンテナが1-2本表示の場所でも5本表示されるようになった。