A personal communications service (PCS) is set of communications capabilities that provide a combination of terminal mobility, personal mobility, and service profile management. This class of services comprises several types of wireless voice or wireless data communications systems, typically incorporating digital technology, providing services similar to advanced cellular mobile or paging services. In addition, PCS can also be used to provide other wireless communications services, including services that allow people to place and receive communications while away from their home or office, as well as wireless communications to homes, office buildings and other fixed locations. Described in more commercial terms, PCS is a generation of wireless cellular-phone technology, that combines a range of features and services surpassing those available in analogue- and first-generation (2G) digital-cellular phone systems, providing a user with an all-in-one wireless phone, paging, messaging, and data service.

The International Telecommunication Union (ITU) describes personal communications services as a component of the IMT-2000 (3G) standard. PCS and the IMT-2000 standard of which PCS is a part do not specify a particular air interface and channel access method. Wireless service providers may deploy equipment using any of several air interface and channel access methods, as long as the network meets the service description characteristics described in the standard.

In ITU Region 2, PCS are provided in the '1900 MHz' band (specifically 1850–1995 MHz). This frequency band was designated by the United States Federal Communications Commission (FCC) and Industry Canada to be used for new wireless services to alleviate capacity caps inherent in the original Advanced Mobile Phone System (AMPS) and Digital AMPS (D-AMPS) cellular networks in the '850 MHz' band (specifically 814–894 MHz). These frequency bands are particular to North America, and other frequency bands may be designated in other regions.