burden but results in all users being able to use any available radio channel. Therefore spectrum effi- Two families of analogue CT have been standardised; that based on ciency in terms of traffic carried per megahertz per square kilometre the original North American standard (h.f./v.h.f.) and a later higher is very much increased compared to a factory set single channel capacity European development operating in the 900 MHz band. system of the type considered in the last section. The benefits of DCS shows when the total cordless traffic demand in a localised area is such that co-channel interference from other users becomes 49.1.2 H.f./v.h.f. analogue CT the dominating factor in terms of speech quality and range of operation. In order to compete on equal price terms with the import of illegal Technically the CEPT standard is a major step forward in cordless North American standard product, many countries chose to adopt product design but is consequently more expensive than the far the same standard with or without technical design changes. In simpler h.f./v.h.f. analogue design. It has, therefore, not achieved Europe the UK and France followed this course, making changes to the degree of market penetration throughout Europe as its proposers the design that avoided radio frequency allocation and transmission had originally predicted. quality problems, but did not significantly increase the basic pro- duction cost. One major change was to incorporate some form of dialling and incoming call security that ensured only the legitimate handset was 49.2 Digital technology able to open up and receive a call from its associated base station. This stopped the accidental, or sometimes deliberate, practice of The analogue cordless telephone has succeeded in opening up the long distance calls being dialled over a neighbour's cordless termi- market for localised mobility around the home or place of work, nal with consequent misdirection of the call charge. The basic without incurring the costs and regulation associated with a 