Call logging in a wireless telecommunications system

DETAILED DESCRIPTION OF THE INVENTION FIG.
1 is a schematic overview of an example of a wireless telecommunications system.
The telecommunications system includes one or more service areas 12, 14 and 16, each of which is served by a respective central terminal (CT) 10 which establishes a radio link with subscriber terminals (ST) 20 within the area concerned.
The area which is covered by a central terminal 10 can vary.
For example, in a rural area with a low density of subscribers, a service area 12 could cover an area with a radius of 15-20 Km.
A service area 14 in an urban environment where is there is a high density of subscriber terminals 20 might only cover an area with a radius of the order of 100 m.
In a suburban area with an intermediate density of subscriber terminals, a service area 16 might cover an area with a radius of the order of 1 Km.
It will be appreciated that the area covered by a particular central terminal 10 can be chosen to suit the local requirements of expected or actual subscriber density, local geographic considerations, etc, and is not limited to the examples illustrated in FIG.
1.
Moreover, the coverage need not be, and typically will not be circular in extent due to antenna design considerations, geographical factors, buildings and so on, which will affect the distribution of transmitted signals.
The central terminals 10 for respective service areas 12, 14, 16 can be connected to each other by means of links 13, 15 and 17 which interface, for example, with a public switched telephone network (PSTN) 18.
The links can include conventional telecommunications technology using copper wires, optical fibres, satellites, microwaves, etc.
The wireless telecommunications system of FIG.
1 is based on providing fixed microwave links between subscriber terminals 20 at fixed locations within a service area (e.
g.
, 12, 14, 16) and the central terminal 10 for that service area.
In a preferred embodiment each subscriber terminal 20 is provided with a permanent fixed access link to its central terminal 10