According to Phil Schiller, a key figure at Apple, the “S” in “3GS” stands for “Speed.”[7] Improvements include performance, a 3-megapixel camera with higher resolution and video ability, voice control,[8] and support for 7.2 Mbit/s HSDPA downloads.

[15] After the release of the iPhone 4S, the 3GS was still offered for free on a contract until November 2011, when AT&T raised the price to 59 cents with no explanation.

[17] Though in addition to the upgrades mainly regarding performance, various software features were also introduced exclusively to the iPhone 3GS such as video recording, voice control, and digital compass.

As on previous models, all data is stored in flash memory and not in the SIM and it does not offer any options to expand storage.

The iPhone 3GS is powered by an internal 3.7 V 1220 mAh rechargeable lithium-ion polymer battery and is designed to retain up to 80% of its original capacity after 400 full charge and discharge cycles.

[24] A magnetometer is also built-in the iPhone 3GS, which is used to measure the strength and/or direction of the magnetic field in the vicinity of the device.

VoiceOver is a feature that dictates music details, system menus, text, and other things that were first introduced on the third generation iPod shuffle.

The iPhone 3GS retains the design of the 3G, with a glossy plastic back with tapered edges and metal buttons.

Walt Mossberg of The Wall Street Journal described the device packed with "new features that makes a great product even better, but for many users, the software may be enough of a boost to keep them from buying the new model.

CNET gave the iPhone 3GS 4 out of 5 stars, citing battery life improvements and speed bump.

[32] It is also worth pointing out the temperature specifications in which the iPhone should be operated, which follows safety standards in the countries the 3GS was released.

Unlike the iPhone 3G, it received support for features like home screen wallpapers and multitasking.

On September 9, 2009, Apple launched an updated model of the iPhone 3GS that patched a segment overflow in the SecureROM of the Device that had allowed loading an unsigned LLB.

[36] On September 12, 2012, Apple announced that they would no longer be selling and supporting the iPhone 3GS and the device did not receive iOS 7, due to hardware limitations.

[37] On February 21, 2014, Apple issued iOS 6.1.6 to fix the "goto fail;" SSL security bug.