The gateway exchange is the center at which the international exchange multiplex equipment and ancillary equipment, for international telephone and/or telegraph, Telex data, Television and Facsimile are located. The gateway exchange is an international transit exchange-(A transit exchange is that to which no subscribers are connected directly but it serves as switching centers among different exchanges, it also serves as tandem exchange), to which different transit exchanges are connected. The gateway exchange connects the subscribers to an exchange outside the country.
All international trunks of a country are connected to the gateway exchange. The international trunks are brought to the international gateway from their points of arrival, by cable transmission systems and line-of-sight microwave radio systems. The international exchange perform the following two functions:
- International gateway: providing a means of connecting calls from the national system of a country to the international network.
- Trunk exchange: It acts as a trunk exchange for calls connected between other countries.
The block diagram of a call from country A to country B may be connected over the international gateway exchange are shown in the figure,