Networks or facilities — The ensemble of equipment, sites, switches, lines, circuits, software, and other transmission apparatus  used to provide telecommunications services.

Public network — A country's telephone system, including local loops, exchanges, trunks, and international links for providing telephone service to the general public. 

Non-public (private) network — Any network used to communicate within an organization (as distinct from providing service to the public) or to supply such communications to organizations, based on a configuration of own or leased facilities. The term includes networks used by private companies, state enterprises, or government entities.  Self-use of private networks and services is addressed by the GATS Annex on Telecommunications, whereas the ability of competitive providers to sell use of such networks and services to organizations is addressed through commitments taken in GATS schedules. 

Facilities-based service supplier (or operator) — A telecommunications service provider owning, as opposed to leasing, networks used to provide telecommunications services. 

Resale-based service supplier — The subsequent sale or lease on a commercial basis, with or without adding value, of a service provided by a facilities-based telecommunications operator. A resale service supplier or reseller is a company that leases bulk-rated plant (e.g. transmission) capacity from facilities-based carriers and uses that capacity to provide services to individual customers or groups of customers at prices high enough to make a profit yet sufficiently below the equivalent rates of the facilities-based carriers to attract customers. 

Bypass — Arrangements or facilities whereby a customer can access long-distance, international, or other services without using the local operating company's switched network, thus avoiding payment of access charges. More generally, any means whereby customers avoid usage of a monopoly service or facility. 

Interconnection/Interconnection charge — A charge levied by network operators on other service providers to recover the costs of the interconnection facilities (including the hardware and software for routing, signalling, and other basic service functions) provided by the network operators. 

Tariff/Unbundled Tariff — Tariffs are the schedule of rates and regulations governing the provision of telecommunications services. Unbundling of tariffs is where each component of a communications service or product is priced separately, so that customers may select only those components needed and be charged accordingly. 

Cost-based pricing — The general principle of charging for services in relation to the cost of providing these services. 

Cross-subsidization — The practice of using profits generated from one product or service to support another provided by the same operating entity. 

Universal service — The concept that every individual within a country should have basic telephone service available at an affordable price. The concept varies, among countries, from having a telephone in every home and business in the wealthier countries to most inhabitants' being within a certain distance or time away from a public telephone in developing countries. 

Frequency, spectrum/spectrum management — The spectrum or range of radio frequencies available for communication, industrial, and other uses. Frequency bands or segments are assigned to various categories of users for specific purposes, such as commercial radio and television, terrestrial microwave links, satellites, and police. At the international level this is done by the International Frequency Registration Board (IFRB) of the International Telecommunication Union (ITU). Individual national regulatory agencies monitor the occupancy of the radio spectrum and allocate frequencies to individual users or a groups of users so as to enable a large number of services to operate within specified limits of interference. 

Packet-switched data transmission — A data communications service in which a data stream is divided into units called packets that are separately routed to a destination where the original message is then reconstituted. 

Private leased circuit service — The service of providing permanent transmission connection between two customer premises for the exclusive use by a customer. This service may be provided over facilities owned or operated by an operator or over transmission capacity sold or leased by a non-facilities-based telecommunications provider, or reseller, and may use terrestrial or satellite facilities. It generally does not involve central office switching operations. Also called a private leased lines. 

Mobile services — Radiocommunications services between ships, aircraft, road vehicles, or hand-held terminal stations for use while in motion or between such stations and fixed points on land. 

Cellular service — A terrestrial radio-based service providing two-way communications by dividing the serving area into a regular pattern of sub-areas or cells, each with a base station having a low-power transmitter and receiver. Although cellular radio is primarily a means of providing mobile telephone service, it is also used to provide data services and private voice services, and as an alternative to fixed wired telephone service where this is scarce, such as in developing countries. 

Paging service — A service that allows transmitting a signal, usually only an alarm tone, via radio from any telephone in the public-switched network to a personal, portable receiving device in a defined operating area. More sophisticated systems provide audible or visual display messages. 

Trunked radio system — A method of operation in which a number of radio frequency channel pairs are assigned to mobile and base stations in the system for use as a trunk group. 

Personal communications systems or services — A service that enables access to telecommunications services by allowing personal mobility. It enables each user to participate in a user-defined set of subscribed services as well as to initiate and receive calls on the basis of a unique, personal, network-independent number. It can be used across multiple networks at any fixed, movable, or mobile terminal regardless of geographical location. 

Teleconferencing/Videoconferencing — A two-way telecommunications service that allows live video images and speech of participants in a conference to be transmitted between two or more locations. Videoconferencing services generally require digital transmission.