iPhone 4S (4s)

Although it shares its appearance with the preceding iPhone 4, the iPhone 4S* is significantly more powerful and famously introduced Siri, a voice-controlled "intelligent assistant."

Similar to the iPhone 4, the iPhone 4S features the same stainless steel body design, a 3.5-inch 960x640 (326 ppi) IPS LED-backlit "retina" display, dual noise-canceling microphones, and integrated antennas in the metal band. The device has a chemically hardened "aluminosilicate" glass front and back (available in black or white), with an "oleophobic" coating on both surfaces.

However, the iPhone 4S is a "world phone," supporting both GSM and CDMA networks (UMTS/HSDPA/HSUPA at 850/900/1900/2100 MHz; GSM/EDGE at 850/900/1800/1900 MHz; and CDMA EV-DO Rev. A at 800/1900 MHz), with an antenna that automatically switches modes. It also supports 802.11b/g/n, Bluetooth 4.0, and HSDPA speeds up to 14.4 Mbps.

The iPhone 4S also upgrades its cameras, featuring a rear 8-megapixel camera that shoots 1080p HD video at 30 FPS with a "backside illuminated sensor" and an LED flash, plus a front-facing VGA camera for FaceTime video calls over Wi-Fi.

It is powered by a dual-core "Apple A5" processor, has 512 MB of RAM, and was offered in 8 GB, 16 GB, 32 GB, or 64 GB storage capacities (32/64 GB options discontinued Sept 12, 2012; 16 GB replaced by an 8 GB option on Sept 10, 2013; 8 GB option discontinued Sept 9, 2014).

Apple's battery life estimates are up to 40 hours of audio, 14 hours of 2G talk time, 8 hours of 3G talk time, 6 hours of 3G internet use, 9 hours of Wi-Fi internet use, 10 hours of video playback, and 200 hours of standby.

In the US, the iPhone 4S was initially available on AT&T, Sprint, or Verizon with 16/32/64 GB of storage for US$199/US$299/US$399, respectively, with a two-year contract. It was also sold unlocked and contract-free for US$649/US$749/US$849. On Sept 12, 2012, the 16 GB locked model dropped to US$99 and the unlocked version to US$549. On Sept 10, 2013, a new 8 GB model was introduced at US$0 locked or US$450 unlocked, before being discontinued on Sept 9, 2014. Note that the unlocked model is blocked from working on CDMA networks.

*For detail-oriented readers, Apple quietly renamed the iPhone 4S to iPhone 4s on September 10, 2013, likely for consistency with the new iPhone 5s.

The iPhone 4S commanded extraordinary acclaim from technology critics who recognized Siri as a groundbreaking leap forward in human-computer interaction that fulfilled decades-old aspirations for natural language computing. Professional reviewers universally praised the device's dual-core A5 processor for delivering blazing performance improvements, while the upgraded 8-megapixel camera system earned accolades for bringing professional-quality photography capabilities to a smartphone. Despite its identical exterior design to the iPhone 4, technology journalists emphasized that the internal advances represented far more than an incremental update, with many declaring Siri alone worth the upgrade price. Industry analysts particularly noted how the iPhone 4S marked Apple's most successful product launch to date, validating the company's strategy of perfecting existing designs while introducing revolutionary new features that redefined user expectations for mobile technology.