A mobile phone, cell phone, cellphone, or hand phone, sometimes shortened to simply mobile, cell or just phone, is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). Modern mobile telephone services use a cellular network architecture, and, therefore, mobile telephones are called cellular telephones or cell phones, in North America.

In addition to telephony, 2000s-era mobile phones support a variety of other services, such as text messaging, MMS, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, video games, and digital photography. Mobile phones offering only those capabilities are known as feature phones; mobile phones which offer greatly advanced computing capabilities are referred to as smartphones.

The first handheld mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing c. 2 kilograms (4.4 lbs). In 1979, Nippon Telegraph and Telephone (NTT) launched the world’s first cellular network in Japan. In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. From 1983 to 2014, worldwide mobile phone subscriptions grew to over seven billion—enough to provide one for every person on Earth. In first quarter of 2016, the top smartphone developers worldwide were Samsung, Apple, and Huawei, and smartphone sales represented 78 percent of total mobile phone sales. For feature phones (or “dumbphones”) as of 2016, the largest were Samsung, Nokia, and Alcatel.

A handheld mobile radio telephone service was envisioned in the early stages of radio engineering. In 1917, Finnish inventor Eric Tigerstedt filed a patent for a “pocket-size folding telephone with a very thin carbon microphone”. Early predecessors of cellular phones included analogue radio communications from ships and trains. The race to create truly portable telephone devices began after World War II, with developments taking place in many countries. The advances in mobile telephony have been traced in successive “generations”, starting with the early zeroth-generation (0G) services, such as Bell System’s Mobile Telephone Service and its successor, the Improved Mobile Telephone Service. These 0G systems were not cellular, supported few simultaneous calls, and were very expensive.

The first handheld cellular mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing 2 kilograms (4.4 lb). The first commercial automated cellular network (1G) analogue was launched in Japan by Nippon Telegraph and Telephone in 1979. This was followed in 1981 by the simultaneous launch of the Nordic Mobile Telephone (NMT) system in Denmark, Finland, Norway, and Sweden. Several other countries then followed in the early to mid-1980s. These first-generation (1G) systems could support far more simultaneous calls but still used analogue cellular technology.

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In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone.

In 1991, the second-generation (2G) digital cellular technology was launched in Finland by Radiolinja on the GSM standard. This sparked competition in the sector as the new operators challenged the incumbent 1G network operators.

Ten years later, in 2001, the third generation (3G) was launched in Japan by NTT DoCoMo on the WCDMA standard. This was followed by 3.5G, 3G+ or turbo 3G enhancements based on the high-speed packet access (HSPA) family, allowing UMTS networks to have higher data transfer speeds and capacity.

By 2009, it had become clear that, at some point, 3G networks would be overwhelmed by the growth of bandwidth-intensive applications, such as streaming media. Consequently, the industry began looking to data-optimized fourth-generation technologies, with the promise of speed improvements up to ten-fold over existing 3G technologies. The first two commercially available technologies billed as 4G were the WiMAX standard, offered in North America by Sprint, and the LTE standard, first offered in Scandinavia by TeliaSonera.

5G is a technology and term used in research papers and projects to denote the next major phase in mobile telecommunication standards beyond the 4G/IMT-Advanced standards. The term 5G is not officially used in any specification or official document yet made public by telecommunication companies or standardization bodies such as 3GPP, WiMAX Forum or ITU-R. New standards beyond 4G are currently being developed by standardization bodies, but they are at this time seen as under the 4G umbrella, not for a new mobile generation.

Smartphones have a number of distinguishing features. The International Telecommunication Union measures those with Internet connection, which it calls Active Mobile-Broadband subscriptions (which includes tablets, etc.). In the developed world, smartphones have now overtaken the usage of earlier mobile systems. However, in the developing world, they account for around 50% of mobile telephony.

Feature phone is a term typically used as a retronym to describe mobile phones which are limited in capabilities in contrast to a modern smartphone. Feature phones typically provide voice calling and text messaging functionality, in addition to basic multimedia and Internet capabilities, and other services offered by the user’s wireless service provider. A feature phone has additional functions over and above a basic mobile phone which is only capable of voice calling and text messaging. Feature phones and basic mobile phones tend to use a proprietary, custom-designed software and user interface. By contrast, smartphones generally use a mobile operating system that often shares common traits across devices.

There are Orthodox Jewish religious restrictions which, by some interpretations, standard mobile telephones overstep. To deal with this problem, some rabbinical organizations have recommended that phones with text-messaging capability not be used by children. Phones with restricted features are known as kosher phones and have rabbinical approval for use in Israel and elsewhere by observant Orthodox Jews. Although these phones are intended to prevent immodesty, some vendors report good sales to adults who prefer the simplicity of the devices. Some phones are approved for use by essential workers (such as health, security, and public service workers) on the sabbath, even though the use of any electrical device is generally prohibited during this time.

Mobile phones communicate with cell towers that are placed to give coverage across a telephone service area which is divided up into ‘cells’. Each cell uses a different set of frequencies from neighbouring cells, and will typically be covered by 3 towers placed at different locations. The cell towers are usually interconnected to each other and the phone network and the internet by wired connections. Due to bandwidth limitations each cell will have a maximum number of cell phones it can handle at once. The cells are therefore sized depending on the expected usage density, and may be much smaller in cities. In that case much lower transmitter powers are used to avoid broadcasting beyond the cell.

As a phone moves around, a phone will “hand off”- automatically disconnect and reconnect to the tower that gives the best reception.

Additionally, short-range Wi-Fi infrastructure is often used by smartphones as much as possible as it offloads traffic from cell networks on to local area networks.

The common components found on all phones are:

• A CPU, the processor of phones.
• A battery, providing the power source for the phone functions.
• An input mechanism to allow the user to interact with the phone. These are a keypad for feature phones and touch screens for most smartphones.
• A display which echoes the user’s typing, and displays text messages, contacts, and more.
• Speakers for sound.
• SIM cards and R-UIM cards.

Low-end mobile phones are often referred to as feature phones and offer basic telephony. Handsets with more advanced computing ability through the use of native software applications are known as smartphones.

Mobile phones have central processing units (CPUs), similar to those in computers, but optimised to operate in low power environments.

Mobile CPU performance depends not only on the clock rate (generally given in multiples of hertz) but also the memory hierarchy also greatly affects overall performance. Because of these problems, the performance of mobile phone CPUs is often more appropriately given by scores derived from various standardized tests to measure the real effective performance in commonly used applications.

One of the main characteristics of phones is the screen. Depending on the device’s type and design, the screen fills most or nearly all of the space on a device’s front surface. Many smartphone displays have an aspect ratio of 16:9, but taller aspect ratios became more common in 2017.

Screen sizes are measured in diagonal inches; feature phones generally have screen sizes below 3.5 inches. Phones with screens larger than 5.2 inches are often called “phablets.” Smartphones with screens over 4.5 inches in size are commonly difficult to use with only a single hand, since most thumbs cannot reach the entire screen surface; they may need to be shifted around in the hand, held in one hand and manipulated by the other, or used in place with both hands. Due to design advances, some modern smartphones with large screen sizes and “edge-to-edge” designs have compact builds that improve their ergonomics, while the shift to taller aspect ratios have resulted in phones that have larger screen sizes whilst maintaining the ergonomics associated with smaller 16:9 displays.

Liquid-crystal displays are the most common; others are IPS, LED, OLED, and AMOLED displays. Some displays are integrated with pressure-sensitive digitizers, such as those developed by Wacom and Samsung, and Apple’s “3D Touch” system.

In sound, smartphones and feature phones vary little. Some audio-quality enhancing features, such as Voice over LTE and HD Voice, have appeared and are often available on newer smartphones. Sound quality can remain a problem due to the design of the phone, the quality of the cellular network and compression algorithms used in long distance calls. Audio quality can be improved using a VoIP application over WiFi. Cellphones have small speakers so that the user can use a speakerphone feature and talk to a person on the phone without holding it to their ear. The small speakers can also be used to listen to digital audio files of music or speech or watch videos with an audio component, without holding the phone close to the ear.

The average phone battery lasts 2–3 years at best. Many of the wireless devices use a Lithium-Ion (Li-Ion) battery, which charges 500-2500 times, depending on how users take care of the battery and the charging techniques used. It is only natural for these rechargeable batteries to chemically age, which is why the performance of the battery when used for a year or two will begin to deteriorate. Battery life can be extended by draining it regularly, not overcharging it, and keeping it away from heat.

Mobile phones require a small microchip called a Subscriber Identity Module or SIM card, in order to function. The SIM card is approximately the size of a small postage stamp and is usually placed underneath the battery in the rear of the unit. The SIM securely stores the service-subscriber key (IMSI) and the K_i used to identify and authenticate the user of the mobile phone. The SIM card allows users to change phones by simply removing the SIM card from one mobile phone and inserting it into another mobile phone or broadband telephony device, provided that this is not prevented by a SIM lock. The first SIM card was made in 1991 by Munich smart card maker Giesecke & Devrient for the Finnish wireless network operator Radiolinja.

A hybrid mobile phone can hold up to four SIM cards, with a phone having an IMEI per SIM Card. SIM and R-UIM cards may be mixed together to allow both GSM and CDMA networks to be accessed. From 2010 onwards, such phones became popular in emerging markets, and this was attributed to the desire to obtain the lowest on-net calling rate.

A mobile app is a computer program designed to run on a mobile device, such as a smartphone. The term “app” is a shortening of the term “software application”.

A common data application on mobile phones is Short Message Service (SMS) text messaging. The first SMS message was sent from a computer to a mobile phone in 1992 in the UK while the first person-to-person SMS from phone to phone was sent in Finland in 1993. The first mobile news service, delivered via SMS, was launched in Finland in 2000 and subsequently many organizations provided “on-demand” and “instant” news services by SMS. Multimedia Messaging Service (MMS) was introduced in 2001.

From 1983 to 1998, Motorola was market leader in mobile phones. Nokia was the market leader in mobile phones from 1998 to 2012. In Q1 2012, Samsung surpassed Nokia, selling 93.5 million units as against Nokia’s 82.7 million units. Samsung has retained its top position since then. In 2017, the top five manufacturers worldwide were Samsung (20.9%), Apple (14.0%), Huawei (9.8%), Oppo (5.7%), and Vivo (6.5%). During Q2 2018, Huawei overtook Apple as the world’s second-largest phone manufacturer.

The world’s largest individual mobile operator by number of subscribers is China Mobile, which has over 902 million mobile phone subscribers as of June 2018. Over 50 mobile operators have over ten million subscribers each, and over 150 mobile operators had at least one million subscribers by the end of 2009. In 2014, there were more than seven billion mobile phone subscribers worldwide, a number that is expected to keep growing.

Mobile phones are used for a variety of purposes, such as keeping in touch with family members, for conducting business, and in order to have access to a telephone in the event of an emergency. Some people carry more than one mobile phone for different purposes, such as for business and personal use. Multiple SIM cards may be used to take advantage of the benefits of different calling plans. For example, a particular plan might provide for cheaper local calls, long-distance calls, international calls, or roaming.

The mobile phone has been used in a variety of diverse contexts in society. For example:

• A study by Motorola found that one in ten mobile phone subscribers have a second phone that is often kept secret from other family members. These phones may be used to engage in such activities as extramarital affairs or clandestine business dealings.
• Some organizations assist victims of domestic violence by providing mobile phones for use in emergencies. These are often refurbished phones.
• The advent of widespread text-messaging has resulted in the cell phone novel, the first literary genre to emerge from the cellular age, via text messaging to a website that collects the novels as a whole.
• Mobile telephony also facilitates activism and public journalism being explored by Reuters and Yahoo! and small independent news companies such as Jasmine News in Sri Lanka.
• The United Nations reported that mobile phones have spread faster than any other form of technology and can improve the livelihood of the poorest people in developing countries, by providing access to information in places where landlines or the Internet are not available, especially in the least developed countries. Use of mobile phones also spawns a wealth of micro-enterprises, by providing such work as selling airtime on the streets and repairing or refurbishing handsets.
• In Mali and other African countries, people used to travel from village to village to let friends and relatives know about weddings, births, and other events. This can now be avoided in areas with mobile phone coverage, which are usually more extensive than areas with just land-line penetration.
• The TV industry has recently started using mobile phones to drive live TV viewing through mobile apps, advertising, social TV, and mobile TV. It is estimated that 86% of Americans use their mobile phone while watching TV.
• In some parts of the world, mobile phone sharing is common. Cell phone sharing is prevalent in urban India, as families and groups of friends often share one or more mobile phones among their members. There are obvious economic benefits, but often familial customs and traditional gender roles play a part. It is common for a village to have access to only one mobile phone, perhaps owned by a teacher or missionary, which is available to all members of the village for necessary calls.

The effect of mobile phone radiation on human health is the subject of recent interest and study, as a result of the enormous increase in mobile phone usage throughout the world. Mobile phones use electromagnetic radiation in the microwave range, which some believe may be harmful to human health. A large body of research exists, both epidemiological and experimental, in non-human animals and in humans. The majority of this research shows no definite causative relationship between exposure to mobile phones and harmful biological effects in humans. This is often paraphrased simply as the balance of evidence showing no harm to humans from mobile phones, although a significant number of individual studies do suggest such a relationship, or are inconclusive. Other digital wireless systems, such as data communication networks, produce similar radiation.

A study by the London School of Economics found that banning mobile phones in schools could increase pupils’ academic performance, providing benefits equal to one extra week of schooling per year.

Studies have shown that around 40–50% of the environmental impact of mobile phones occurs during the manufacture of their printed wiring boards and integrated circuits.

The average user replaces their mobile phone every 11 to 18 months, and the discarded phones then contribute to electronic waste. Mobile phone manufacturers within Europe are subject to the WEEE directive, and Australia has introduced a mobile phone recycling scheme.

Apple Inc. had an advanced robotic disassembler and sorter called Liam specifically for recycling outdated or broken iPhones.

Demand for metals used in mobile phones and other electronics fuelled the Second Congo War, which claimed almost 5.5 million lives. In a 2012 news story, The Guardian reported: “In unsafe mines deep underground in eastern Congo, children are working to extract minerals essential for the electronics industry. The profits from the minerals finance the bloodiest conflict since the second world war; the war has lasted nearly 20 years and has recently flared up again. For the last 15 years, the Democratic Republic of the Congo has been a major source of natural resources for the mobile phone industry.”

The company Fairphone has worked to develop a mobile phone that does not contain conflict minerals.