telephony Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is i ...

, an international gateway exchange is a

telephone switch telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital syste ...

that forms the gateway between a national telephone network and one or more other international gateway exchanges, thus providing cross-border connectivity.

Requirements

Whereas international gateway exchanges are commonly implemented using hardware that could also serve to build a Class 4 (national transit) switch, some of the differences between an international gateway exchange and a Class 4 switch include: * International variants of signalling protocols, such as International ISUP and #5, in addition to the relevant national signalling protocols. * Support for

echo canceller Echo suppression and echo cancellation are methods used in telephony to improve voice quality by preventing echo from being created or removing it after it is already present. In addition to improving subjective audio quality, echo suppression ...

s. * Support for DCME * Support for international accounting and settlement agreements. * Support for

A-law An A-law algorithm is a standard companding algorithm, used in European 8-bit PCM digital communications systems to optimize, i.e. modify, the dynamic range of an analog signal for digitizing. It is one of two versions of the G.711 standar ...

/ mu-law transcoding * High capacity (some of the largest telephone exchanges in the world are international gateway exchanges). * Support for the

numbering plan A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, reac ...

s of each of the countries that may be dialed. * Advanced traffic routing capabilities, in order to take advantage of the best available tariffs for each destination. Telephone exchanges {{telephony-stub