The system of St. Louis was acquaintance with the name Urban System. .
• In 1947 were installed a second system for the cover of communication needs of users which were moved in the motorway New York - Boston. This system used frequency in the band 35-44 MHz. This system was acquaintance with the name Highway System.
In 1964 functioned a new system in the 150 MHz, which was acquaintance called MJ and in year 1969 was installed and functioned system MK, using frequencies in the band of radio-spectrum of 450 MHz. It should be marked that so much the MJ as the MK, were departments of Improved System of Mobile Telephony (Improved Mobile Telephone System - IMTS).
In our season, the frequent requirement to be connected (being-line) continuity and everywhere led to the need to be released from the land communication infrastructure and to turn itself in wireless communications, what in deed many times they even have an advantage there that has been established they are used wire. For example if it is difficult we link two networks in two different buildings with optical fibber (soil, cost, authorisations) is in my interest to use wireless methods.
The basic however question is if a complete wireless network can cover the needs of an enterprise. As we all know today, the enterprises do not limit in a specific location. They are also extended in other geographic spaces, very probably and in the abroad provided that exists the possibility. Exists also the case, an enterprise it has in disposal more than one subsidiary companies in the same geographic location. As it is known, between those subsidiary companies it should exists continuing communication for the right operation and the co-ordination of enterprise. The calls that become daily between them are hundreds. .
All these led the businessmen to winds up in some type of network that undertakes the continuing communication between the subsidiary companies (voice and data) and it covers whoever other needs can.