Abstract
M.Comm.
A modern electronic telephone exchange is very flexible in terms of size.
Such exchanges can vary in size from a few lines to more than 50 000 lines.
They can be expanded at any time to cater for more subscribers. This means
that the telecommunications service provider is able to build the exchange just
large enough to supply service to the subscribers in the area, and then
expand the exchange on a regular basis as needed to cater for any growth in
demand for exchange connections. The main advantage of this flexible
approach is that money is not tied up in very expensive exchange equipment
which is not being used.