In telephony

Telephony

In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....

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

Common requirements for International Gateway Exchanges

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 cancellers.
• Support for DCME
• Support for international accounting and settlement agreements.
• Support for A-law
  A-law algorithm
  An A-law algorithm is a standard companding algorithm, used in European digital communications systems to optimize, i.e., modify, the dynamic range of an analog signal for digitizing.It is similar to the μ-law algorithm used in North America and Japan....
  
  /mu-law
  Mu-law algorithm
  The µ-law algorithm is a companding algorithm, primarily used in the digital telecommunication systems of North America and Japan. Companding algorithms reduce the dynamic range of an audio signal...
  
   transcoding
• High capacity (some of the largest telephone exchanges in the world are international gateway exchanges).
• Support for the numbering plans 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.