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A phone is a telecommunications device that enables two-way voice communication, and increasingly data transmission, over distance. There are wired landline phones that connect to the public switched telephone network (PSTN) through copper or fiber, and wireless or mobile phones that connect via radio networks or Internet protocols. The term also covers smartphones, which are networked devices capable of voice calls, messaging, and a wide range of data services.

Invention and evolution: The electrical telephone was developed in the 1870s, with Alexander Graham Bell credited for the first practical device. Early telephones used manual or electromechanical switching. Digital technology and automated switching in the 20th century led to clearer signals, more features, and international interoperability. Mobile telephony began in the late 20th century, expanding from car phones to handheld devices, and smartphones transformed these devices into compact computers.

Types and components: Landline phones are anchored to a fixed network interface and may include a handset, dial mechanism, and base. Mobile phones contain a processor, radio transceiver, SIM card, battery, and display. Smartphones add operating systems, sensors, cameras, and access to applications.

Connectivity and services: Voice calls remain central, but text messaging, voicemail, and data services are common. Cellular networks (GSM, CDMA, LTE/5G) provide wireless access, while Voice over IP (VoIP) uses Internet connections. Multidevice ecosystems and roaming arrangements link phones with other devices and networks.

Impact: Phones have shaped communication, commerce, and culture, while raising concerns about privacy, security, and the digital divide.