Specifications
Apple publishes a full description of the iPhone 3G's technical specifications. Specifications for the original model were available before the release of the 3G model.

Features common to both versions
• Screen size: 3.5 in (89 mm)
• Screen resolution: 480×320 pixels at 163 ppi, with 3:2 aspect ratio
• Input devices: Multi-touch screen interface plus a "Home" button and "Sleep/Wake" located on the top of the iPhone.
• Built-in rechargeable, non-removable battery
• 2 megapixel camera
• Location finding by detection of cell towers and Wi-Fi networks
• Samsung ARM1176JZ(F)-S v1.0 (620 MHz underclocked to 412 MHz, 32-bit RISC; PowerVR MBX 3D graphics co-processor)
• Memory: 128 MB DRAM
• Storage: 8 GB or 16 GB flash memory
• Operating System: iPhone OS
• Quad band GSM / GPRS / EDGE: GSM 850 / 900 / 1800 / 1900
• Wi-Fi (802.11b/g)
• Bluetooth 2.0 with EDR
• 20Hz to 20kHz frequency response (both internal and headset)

Screen and input
The 9 cm (3.5 in) liquid crystal display (320×480 px at 6.3 px/mm, 160 ppi) HVGA touchscreen with scratch-resistant glass is specifically created for use with a finger, or multiple fingers for multi-touch sensing. Because the screen is a capacitive touchscreen, bare skin is required. Most gloves or a stylus prevent the necessary electrical conductivity. The screen is also capable of rendering up to 262,144 colors.
The display responds to three sensors. A proximity sensor shuts off the display and touchscreen when the iPhone is brought near the face during a call. This is done to save battery power and to prevent inadvertent inputs from the user's face and ears. An ambient light sensor adjusts the display brightness which in turn saves battery power. A 3-axis accelerometer senses the orientation of the phone and changes the screen accordingly. Photo browsing, web browsing, and music playing support both upright and left or right widescreen orientations. Later, a software update allowed the first generation iPhone to use cell towers and Wi-Fi networks for location finding despite lacking a hardware GPS. The iPhone 3G supplements those methods with A-GPS.
The iPhone has three physical switches on the sides: wake/sleep, volume up/down, and ringer on/off. These are made of plastic on the original iPhone and metal on the iPhone 3G. A single "home" hardware button below the display brings up the main menu. The touch screen furnishes the remainder of the user interface.
The back of the original iPhone was made of aluminum with a black plastic accent. The iPhone 3G features a full plastic back to increase GSM signal strength. The plastic is black for the 8 GB model, but the 16 GB version is also available in white.

Audio
Loudspeakers are located above the screen and the left side of the bottom of the unit; the microphone is located on the right. Volume controls are located on the left side of the unit and as a slider in the iPod application. Both speakers are used for handsfree operations and media playback.
The 3.5 mm TRRS connector for the headphones is located on the top left corner of the device. The headphone socket on the original iPhone is recessed into the casing, making it incompatible with most headsets without the use of an adapter. The iPhone 3G has a flush mounted headphone socket that eliminates the issue.
The iPhone's headphones are similar to those of most current smartphones, incorporating a microphone. A multipurpose button in the microphone can be used to play or pause music, skip tracks, and answer or end phone calls without touching the iPhone; newer versions also incorporate volume controls. A small number of third-party headsets specifically designed for the iPhone also include a microphone and control button. Wireless earpieces that use Bluetooth technology to communicate with the iPhone are sold separately. They do not support stereo audio.
Composite or component video at up to 576i and stereo audio can be output from the dock connector using an adapter sold by Apple. Unlike many similar phones, the iPhone requires third party software to support voice recording.

Battery
The iPhone features an internal rechargeable battery. It is not user-replaceable, similar to the batteries of existing iPods, and unlike those of most existing cellular phones. If the battery malfunctions or dies prematurely, the phone can be returned to Apple and replaced for free while still under warranty. The warranty lasts one year from purchase and is extended to two years with AppleCare. The cost of having Apple provide a new battery and replace it when the iPhone is out of warranty is slightly less than half the cost of a new 8 GB iPhone.
Since July 2007 third party battery replacement kits have been available at a much lower price than Apple's own battery replacement program. These kits often include a small screwdriver and an instruction leaflet, but as with many newer iPod models the battery in the original iPhone has been soldered in. Therefore a soldering iron is required to install the new battery. The iPhone 3G uses a different battery fitted with a connector, although replacing the battery oneself still voids the warranty.
The original iPhone's battery was stated to be capable of providing up to seven hours of video, six hours of web browsing, eight hours of talk time, 24 hours of music or up to 250 hours on standby. Apple's site says that the battery life "is designed to retain up to 80% of its original capacity after 400 full charge and discharge cycles", which is comparable to the iPod batteries.
The iPhone 3G's battery is stated to be capable of providing up to seven hours of video, six hours of web browsing on Wi-Fi or five on 3G, ten hours of 2G talk time, or five on 3G, 24 hours of music, or 300 hours of standby.
The Foundation for Taxpayer and Consumer Rights, a consumer advocate group, has sent a complaint to Apple and AT&T over the fee that consumers have to pay to have the battery replaced. Though the battery replacement service and its pricing was not made known to buyers until the day the product was launched, a similar service had been well established for the iPods by Apple and various third party service providers.

SIM card
The original iPhone's SIM card slot shown as open, with ejected SIM card.The SIM card is located in a slot at the top of the device. It can be ejected with a paperclip or a tool included with the iPhone 3G. In most countries, the iPhone is usually sold with a SIM lock, which prevents the iPhone from being used on a different mobile network.

Storage
The iPhone was initially released with two options for internal storage size: 4 GB or 8 GB. On September 5, 2007, Apple discontinued the 4 GB models. On February 5, 2008, Apple added a 16 GB model. All data is stored on an internal flash drive; the iPhone does not contain any memory card slots for expanded storage.
Included items
Both the iPhone and the iPhone 3G include (or included) written documentation, stereo earbuds with microphone, a dock connector to USB cable, and a cloth for cleaning the screen. The original iPhone also included a dock to hold the iPhone upright; it is not compatible with the iPhone 3G, for which a slightly different dock is sold separately. The iPhone 3G includes a tool to eject the SIM card; the original model required a paperclip for this purpose. Both versions include a USB power adapter, although iPhone 3Gs sold in North America, Japan, Colombia, Ecuador, or Peru include a more compact version than those bundled with iPhone 3Gs sold elsewhere, or the original model.

Interface
The interface is based around the home screen, a graphical list of available applications. iPhone apps normally run one at a time, although most functionality is still available when making a call or listening to music. The home screen can be accessed at any time by a hardware button below the screen, closing the open application in the process. By default, the Home screen contains the following icons: Text (SMS messaging), Calendar, Photos, Camera, YouTube, Stocks, Maps (Google Maps), Weather, Clock, Calculator, Notes, Settings, iTunes (store), and App Store. Docked at the base of the screen, four icons for Phone, Mail, Safari (Internet), and iPod (music) delineate the iPhone's main purposes. On January 15, 2008, Apple released software update 1.1.3, allowing users to create "Web Clips", home screen icons that resemble apps that open a user-defined page in Safari. After the update, iPhone users can rearrange and place icons on up to nine other adjacent home screens, accessed by a horizontal swipe. Users can also add and delete icons from the dock, which is the same on every home screen. Each home screen holds up to sixteen icons, and the dock holds up to four icons. Users can delete Web Clips and third-party applications at any time, and may select only certain applications for transfer from iTunes. Apple's default programs, however, may not be removed. The 3.0 update will add a system-wide search, known as Spotlight, to the left of the first home screen.
Almost all input is given through the touch screen, which understands complex gestures using multi-touch. The iPhone's interaction techniques enable the user to move the content up or down by a touch-drag motion of the finger. For example, zooming in and out of web pages and photos is done by placing two fingers on the screen and spreading them farther apart or bringing them closer together, an gesture known as "pinching". Scrolling through a long list or menu is achieved by sliding a finger over the display from bottom to top, or vice versa to go back. In either case, the list moves as if it is pasted on the outer surface of a wheel, slowly decelerating as if affected by friction. In this way, the interface simulates the physics of a real object. Other visual effect include horizontally sliding sub-selection, the vertically sliding keyboard and bookmarks menu, and widgets that turn around to allow settings to be configured on the other side. Menu bars are found at the top and bottom of the screen when necessary. Their options vary by program, but always follow a consistent style motif. In menu hierarchies, a "back" button in the top-left corner of the screen displays the name of the parent folder.

Multimedia
The layout of the music library is similar to that of an iPod or current Symbian S60 phones. The iPhone can sort its media library by songs, artists, albums, videos, playlists, genres, composers, podcasts, audiobooks, and compilations. Options are always presented alphabetically, except in playlists, which retain their order from iTunes. The iPhone uses a large font that allows users plenty of room to touch their selection. Users can rotate their device horizontally to landscape mode to access Cover Flow. Like on iTunes, this feature shows the different album covers in a scroll-through photo library. Scrolling is achieved by swiping a finger across the screen.
The iPhone supports gapless playback. Like the fifth generation iPods introduced in 2005, the iPhone can play video, allowing users to watch TV shows and films in widescreen. Unlike other image-related content, video on the iPhone plays only in the landscape orientation, when the phone is turned sideways. Double tapping switches between wide-screen and full-screen video playback.
The iPhone allows users to purchase and download songs from the iTunes Store directly to their iPhone. The feature originally required a Wi-Fi network, but now can use the cellular data network if one is not available.

Accessibility
The iPhone can enlarge text to make it more accessible for vision-impaired users, and can accommodate hearing-impaired users with closed captioning and external TTY devices. Nevertheless, Apple states that "[e]ffective use of the iPhone requires a minimal level of visual acuity, motor skills, and an ability to operate a few mechanical buttons. Use of iPhone by someone who relies solely on audible and tactile input is not recommended." The iPhone 3G has not been rated under the United States Federal Communication Commission guidelines for hearing aid compatibility at either level M3 or T3.

Camera n photo
The iPhone features a built in 2.0 megapixel camera located on the back for still digital photos. It has no optical zoom, flash or autofocus, and does not support video recording. Version 2.0 of iPhone OS introduced the capability to embed location data in the pictures, producing geocoded photographs.
The iPhone includes software that allows the user to upload, view, and e-mail photos. The user zooms in and out of photos by sliding two fingers further apart or closer together, much like Safari. The Camera application also lets users view the camera roll, the pictures that have been taken with the iPhone's camera. Those pictures are also available in the Photos application, along with any transferred from iPhoto or Aperture on a Mac, or Photoshop in Windows

E-mail and text messages
The iPhone also features an e-mail program that supports HTML e-mail, which enables the user to embed photos in an e-mail message. PDF, Word, Excel, and Powerpoint attachments to mail messages can be viewed on the phone. Apple's MobileMe platform offers push email, which emulates the functionality of the popular BlackBerry email solution, for an annual subscription. Yahoo! offers a free push-email service for the iPhone. IMAP (although not Push-IMAP) and POP3 mail standards are also supported, including Microsoft Exchange and Kerio MailServer. In the first versions of the iPhone firmware, this was accomplished by opening up IMAP on the Exchange server. Apple has also licensed Microsoft ActiveSync and now supports the platform (including push email) with the release of iPhone 2.0 firmware. The iPhone will sync e-mail account settings over from Apple's own Mail application, Microsoft Outlook, and Microsoft Entourage, or it can be manually configured on the device itself. With the correct settings, the e-mail program can access almost any IMAP or POP3 account.
Text messages are presented chronologically in a mailbox format similar to Mail, which places all text from recipients together with replies. Text messages are displayed in speech bubbles (similar to iChat) under each recipient's name. The iPhone currently has built-in support for e-mail message forwarding, drafts, and direct internal camera-to-e-mail picture sending. Support for multi-recipient SMS was added in the 1.1.3 software update. Support for MMS is planned for the 3.0 update for the iPhone 3G only. A lack of focus on text-messaging is widely considered a chief weakness of the iPhone, although a large number of users evidently have no issue using the device for this purpose.

Text input
For text input, the iPhone implements a virtual keyboard on the touchscreen. It has automatic spell checking and correction, predictive word capabilities, and a dynamic dictionary that learns new words. The keyboard can predict what word the user is typing and complete it, and correct for the accidental pressing of keys adjacent to the presumed desired key. The keys are somewhat larger and spaced farther apart when in landscape mode, which is supported by only a limited number of applications. Holding a finger over a section of text brings up a magnifying glass, allowing users to place the cursor in the middle of existing text. The virtual keyboard can accommodate 21 languages, including character recognition for Chinese. The iPhone does not currently support cut, copy, or pasting text, but the feature is planned for the 3.0 update.