Query: The IPhone 4 has only a simple mobile operating system.

Relevant passages:
IPhone 4 <=SEP=> The iPhone 4 is a smartphone that was designed and marketed by Apple Inc. . Following a number of notable leaks , the iPhone 4 was first unveiled on June 7 , 2010 , at Apple 's Worldwide Developers Conference in San Francisco , and was released on June 24 , 2010 , in the United States , United Kingdom , France , Germany and Japan . It is the 4th generation of iPhone , succeeding the 3GS and preceding the 4S .   The iPhone 4 introduced a new hardware design to the iPhone family , which Apple 's CEO Steve Jobs touted as the thinnest smartphone in the world at the time ; it consisted of an uninsulated stainless steel frame which doubles as an antenna , with internal components situated between chemically strengthened aluminosilicate glass . The iPhone 4 also introduced Apple 's new high-resolution `` Retina Display '' ; while maintaining the same physical size and aspect ratio as its precursors , its liquid crystal display had a pixel density of 326 pixels per inch . The iPhone 4 also introduced Apple 's A4 system-on-chip , along with iOS 4 -- which notably introduced multitasking functionality and Apple 's new FaceTime video chat service . The iPhone 4 was also the first iPhone to include a front-facing camera , and the first to be released in a version for CDMA networks , ending AT&T 's period as the exclusive carrier of iPhone products in the United States .   It was succeeded as Apple 's flagship smartphone in 2011 by the iPhone 4S . However , iPhone 4 continued to be produced until 2013 .   The iPhone 4 received generally positive reception , with critics praising its revamped design and more powerful hardware in comparison to previous models . While it was a market success , with over 600,000 pre-orders within 24 hours , the release of the iPhone 4 was plagued by highly publicized reports that abnormalities in its new antenna design caused the device to lose its cellular signal if held in a certain way . Most human contact with the phone 's outer edge would cause a significant decrease in signal strength .   The iPhone 4 spent the longest time as Apple 's flagship iPhone model at fifteen months , and had the longest lifespan of any iPhone ever produced , spanning close to four years and available in some developing countries until early 2015 .

Smartphone <=SEP=> A smartphone is a mobile personal computer with an advanced mobile operating system with features useful for mobile or handheld use . Smartphones , which are typically pocket-sized ( as opposed to tablets , which are much larger in measurement ) , have the ability to place and receive voice/video calls and create and receive text messages , have personal digital assistants ( such as Siri , Google Assistant , Alexa , Cortana , or Bixby ) , an event calendar , a media player , video games , GPS navigation , digital camera and digital video camera . Smartphones can access the Internet through cellular or Wi-Fi and can run a variety of third-party software components ( `` apps '' from places like Google Play Store or Apple App Store ) . They typically have a color display with a graphical user interface that covers more than 76 % of the front surface . The display is almost always a touchscreen and sometimes additionally a touch-enabled keyboard like the Priv/Passport BlackBerrys , which enables the user to use a virtual keyboard to type words and numbers and press onscreen icons to activate `` app '' features .   In 1999 , the Japanese firm NTT DoCoMo released the first smartphones to achieve mass adoption within a country . Smartphones became widespread in the late 2000s . Most of those produced from 2012 onward have high-speed mobile broadband 4G LTE , motion sensors , and mobile payment features . In the third quarter of 2012 , one billion smartphones were in use worldwide . Global smartphone sales surpassed the sales figures for regular cell phones in early 2013 .