Communications system

DETAILED DESCRIPTION OF EMBODIMENTS In future telecommunications network architectures the concept of a call may be replaced by that of a session or other concept; in the Telecommunications Information Network Architecture (TINA) for example, the concept of a call is replaced by a `session`, and a query and response is replaced by a sequence of messages within the session).
The invention encompasses such architectures.
Similarly the concept of an originator is proposed to move to an `invoking party` and a terminating party is proposed to move to an `invited party`.
It is understood by those skilled in the art that differing intelligent network standards exist, including the Bellcore AIN releases as well as the ITU IN standards, and that implementations of such standards are often partial in differing geographical regions and individual network operators.
Many networks only use AIN/IN for specific services, and implementations of AIN/IN in many networks are to some degree proprietary.
The descriptions hereinafter borrow from both AIN and IN terminologies, however for those familiar with only one such system there are usually equivalent capabilities in the other system.
Moreover, the standards for `Signalling System No.
7` differ between regions and individual networks, with the US standard being ANSI SS7, and Europe's standard being.
ITU's CCS7; implementations also vary within different networks and territories, with the current signalling standard in the UK for example being set by British Telecommunications plc with their version of the CCS7 standard TUP (Telephone User Part) being implemented in BT-NUP (defined in the BT document BTNR167).
The call drop-back facility for example is not noted in the standard CCS7 TUP, but is noted in BTNR167, and is also planned for later releases of Signalling System No.
7 ISDN User part (ISUP).
As the degree of CCS7 implementation in networks has not been fully rolled out, some of the information and/or call flows have to be realised in a non-ideal way (using "tromboning" where a call cannot be dropped back for example), however this does not affect the essence of the invention, and indeed as the architecture of telecommunications networks evolve, the implementation of the invention will increase in elegance