Global Title

A global title (GT) is an address used in the SCCP protocol for routing signaling messages on telecommunications networks. In theory, a global title is a unique address which refers to only one destination, though in practice destinations can change over time.

The global title is similar in purpose on the PSTN to the host name on the Internet. In design, however, global titles are quite different. The structure is usually hierarchical, the value can be of variable length, and is not necessarily a wholly numeric value—though it often is for issues of backward compatibility and association with regular telephone numbers.

The structure of a global title for ITU-T applications is officially defined in ITU-T Recommendation Q.713, and further extended in the supporting numbering plan standards. Other national variants of Signalling Connection Control Part (SCCP), such as the American National Standards Institute variant specified in ANSI T1.112/2000, define their own format for the Global Title. The value of a global title is a sequence of attributes which modify the address value. To summarize:

A global title can be in a variety of formats, most of which are each defined in separate standards. The format parameter indicates which of the available formats are in use. Each format can include any of the subsequent parameters.

The numbering plan indicator (NPI) describes which numbering plan will be used for the global title. The numbering plan chosen will aid the routing system in determining the correct network system to direct the message.

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