Cellular phone in the context of Radio frequency

Instant messaging (IM) technology is a type of synchronous computer-mediated communication involving the immediate (real-time) transmission of messages between two or more parties over the Internet or another computer network. Originally involving simple text message exchanges, modern instant messaging applications and services (also variously known as instant messenger, messaging app, chat app, chat client, or simply a messenger) tend to also feature the exchange of multimedia, emojis, file transfer, VoIP (voice calling), and video chat capabilities.

Instant messaging systems facilitate connections between specified known users (often using a contact list also known as a "buddy list" or "friend list") or in chat rooms, and can be standalone apps or integrated into a wider social media platform, or in a website where it can, for instance, be used for conversational commerce. Originally the term "instant messaging" was distinguished from "text messaging" by being run on a computer network instead of a cellular/mobile network, being able to write longer messages, real-time communication, presence ("status"), and being free (only cost of access instead of per SMS message sent).

Irradiation is the process by which an object is exposed to radiation. An irradiator is a device used to expose an object to radiation, most often gamma radiation, for a variety of purposes. Irradiators may be used for sterilizing medical and pharmaceutical supplies, preserving foodstuffs, alteration of gemstone colors, studying radiation effects, eradicating insects through sterile male release programs, or calibrating thermoluminescent dosimeters (TLDs).

The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve a specific purpose, rather than radiation exposure to normal levels of background radiation. The term irradiation usually excludes the exposure to non-ionizing radiation, such as infrared, visible light, microwaves from cellular phones or electromagnetic waves emitted by radio and television receivers and power supplies.

Monolithic microwave integrated circuit, or MMIC (sometimes pronounced "mimic"), is a type of integrated circuit (IC) device that operates at microwave frequencies (300 MHz to 300 GHz). These devices typically perform functions such as microwave mixing, power amplification, low-noise amplification, and high-frequency switching. Inputs and outputs on MMIC devices are frequently matched to a characteristic impedance of 50 ohms. This makes them easier to use, as cascading of MMICs does not then require an external matching network. Additionally, most microwave test equipment is designed to operate in a 50-ohm environment.

MMICs are dimensionally small (from around 1 mm to 10 mm) and can be mass-produced, which has allowed the proliferation of high-frequency devices such as cellular phones. MMICs were originally fabricated using gallium arsenide (GaAs), a III-V compound semiconductor. It has two fundamental advantages over silicon (Si), the traditional material for IC realisation: device (transistor) speed and a semi-insulating substrate. Both factors help with the design of high-frequency circuit functions. However, the speed of Si-based technologies has gradually increased as transistor feature sizes have reduced, and MMICs can now also be fabricated in Si technology. The primary advantage of Si technology is its lower fabrication cost compared with GaAs. Silicon wafer diameters are larger (typically 8" to 12" compared with 4" to 8" for GaAs) and the wafer costs are lower, contributing to a less expensive IC.

Intelligent vehicular ad hoc networks (InVANETs) use WiFi IEEE 802.11p (WAVE standard) and effective communication between vehicles with dynamic mobility. Effective measures such as media communication between vehicles can be enabled as well methods to track automotive vehicles. InVANET is not foreseen to replace current mobile (cellular phone) communication standards.

"Older" designs within the IEEE 802.11 scope may refer just to IEEE 802.11b/g. More recent designs refer to the latest issues of IEEE 802.11p (WAVE, draft status). Due to inherent lag times, only the latter one in the IEEE 802.11 scope is capable of coping with the typical dynamics of vehicle operation.

cdmaOne, most often simply referred to as CDMA, is a 2G digital cellular technology. It was the commercial name for Interim Standard 95 (IS-95), a technology that was developed by Qualcomm and later adopted as a standard by the Telecommunications Industry Association in TIA/EIA/IS-95 release published in 1995.

cdmaOne used code-division multiple access (CDMA), a multiple access scheme for digital radio, to send voice, data and signaling data (such as a dialed telephone number) between mobile telephones and cell sites. CDMA transmits streams of bits (PN codes). CDMA permits several radios to share the same frequencies. Unlike time-division multiple access (TDMA), a competing system used in 2G GSM, all radios can be active all the time, because network capacity does not directly limit the number of active radios. Since larger numbers of phones can be served by smaller numbers of cell-sites, CDMA-based standards have a significant economic advantage over TDMA-based standards, or the oldest cellular standards that used frequency-division multiplexing.

Digital AMPS (D-AMPS), most often referred to as TDMA, is a second-generation (2G) cellular phone system that was once prevalent throughout the Americas, particularly in the United States and Canada since the first commercial network was deployed in 1993. Former large D-AMPS networks included those of AT&T and Rogers Wireless. The name TDMA is based on the abbreviation for time-division multiple access, a common multiple access technique which is used in most 2G standards, including GSM. D-AMPS competed against GSM and systems based on code-division multiple access (CDMA). It is now considered end-of-life, as existing networks have shut and been replaced by GSM/GPRS or CDMA2000 technologies. The last carrier to operate a D-AMPS network was U.S. Cellular, who terminated it on February 10, 2009.

The technical names for D-AMPS are IS-54 and its successor IS-136. IS-54 was the first mobile communication system which had provision for security, and the first to employ time-division multiple access (TDMA) technology. IS-136 added a number of features to the original IS-54 specification, including text messaging (SMS), circuit switched data (CSD), and an improved compression protocol. SMS and CSD were both available as part of the GSM protocol, and IS-136 implemented them in a nearly identical fashion.

The MicroTAC is a series of cellular phones that was marketed by Motorola from 1989 until approximately 2000. The MicroTACs pioneered a new "flip" design in cellular handsets that was considered innovative and more compact compared to previous "brick" phones, such as Motorola's own DynaTAC line.

The MicroTAC's design consisted of the "mouthpiece" being folded over the keypad. On later production models the "mouthpiece" was actually located in the base of the phone, along with the ringer. This set the standard and became the model for later clamshell design phones, which Motorola adopted in the StarTAC in 1996.

CT1 (Cordless telephone generation 1) was the first-generation analog cordless telephone standard that was developed by the European Conference of Postal and Telecommunications Administrations (CEPT) in 1984 and used primarily in Europe. The standard defined the technical and operational characteristics for cordless telephones, allowing a wireless handset to communicate with a base station that is connected to the public telephone network. The original frequency allocation included 40 duplex channels using 25 kHz separation, with handsets transmitting in the 914-915 MHz band and base stations transmitting n the 959-960 MHz band. These frequencies overlap with those used by channels 120-124 on GSM cellular phones and thus these original frequencies have been withdrawn from use for cordless phones in the countries that originally authorized them.

CT1+ provided in 1987 for a set of 80 additional channels using the same technical standard with 885–887 MHz used by the phones and 930–932 MHz used by the base stations. The introduction of CT1+ was driven by the increasing demand for cordless telephone channels, as the original 40 channels proved insufficient to support the growing number of users without severe interference problems when multiple handsets operated in the same area. While not part of the original GSM-900 band, the frequencies do overlap with the extended GSM-900 band.

A soft key is a button flexibly programmable to invoke any of a number of functions rather than being associated with a single fixed function or a fixed set of functions. A softkey often takes the form of a screen-labeled function key located alongside a display device, where the button invokes a function described by the text at that moment shown adjacent to the button on the display. Soft keys are also found away from the display device, for example on the sides of cellular phones, where they are typically programmed to invoke functions such as PTT, memo, or volume control. Function keys on keyboards are a form of soft key. In contrast, a hard key is a key with dedicated function such as the keys on a number keypad.

Screen-labeled function keys are today most commonly found in kiosk applications, such as automated teller machines and gas pumps. Screen-label function keys date to aviation applications in the late 1960s. Kiosk applications were particularly common in the 1990s and 2000s. Screen-labeled function keys are found in automotive and aviation applications such as in the primary flight and multi-function displays. An alternative to screen-labeled function keys is buttons (virtual keys) on a touchscreen, where the label is directly pushable. The increased prevalence of touchscreens in the 2000s has led to a decrease in screen-labeled function keys. However, screen-labeled function keys are inexpensive and robust, and provide tactile feedback.

The IBM Simon Personal Communicator (simply known as IBM Simon) is a cellular phone and personal digital assistant (PDA) designed by International Business Machines (IBM), released in 1994. Built on an x86 processor, the IBM Simon features a 4.5 inch resistive touchscreen display and runs an MS-DOS-compatible operating system with the ability to install additional software using its PCMCIA slot, The Simon also has a modem for faxing and email and was also the first PDA to include telephony features (make phone calls) through cellular; due to these features and capabilities, it has retrospectively been referred to as the first true smartphone.

The device was manufactured by Mitsubishi Electric. BellSouth Cellular Corp. distributed the IBM Simon in the United States between August 1994 and February 1995 for use on its analog AMPS network, selling 50,000 units. Sales were hampered by its high price (over $2,100 in 2021 adjusted for inflation) and a short battery life lasting only an hour. IBM worked on a smaller successor model, codenamed Neon, but it was abandoned during development and not released.