The specifications are in every respect the work of the representatives of the Nordic telecom agencies. Haug mentions Poul Sterndorff from Denmark and Lars Ackzell from Sweden in particular, who both devoted a great deal of work to the signal specifications.
“They were generally considered to be some of Europe’s leading experts on signaling in telecom networks,” he says. “Sterndorff was soon able to establish that [Håkan Bokstam’s] 14 commandments could not be attained without overturning strongly held taboos in the telecommunications world. For example, this applied to some of the tariff principles. Counter to previous practice, for example, NMT used a standard tariff.”
The idea was revolutionary in its simplicity.
An important compromise was what became known as the “tromboning” principle, which applies when a call is forwarded to a roaming subscriber.
Haug explains: “If you live in Stockholm but visit Oslo, then a call from a subscriber in Oslo will first go to Stockholm because he has dialed your number. It will then be connected to Oslo because the system says you are there. The call will be charged where it is made on the basis of the number dialed, which is all the Oslo exchange knows, but then payment for the connection from Stockholm to your telephone, in other words to Oslo, will be charged to you as the Stockholm subscriber.
“You may think this is unnecessarily expensive but at this time it was the only way to solve the problem without having to make changes in the fixed network.”
In other words, NMT was regarded as a separate dialing code in each country. Calls to a subscriber were made using the same number irrespective of where he or she might be. This was an enormous advantage for subscribers, and seems obvious today, but it was a radical innovation in the early 1980s.
SIMILARITIES BETWEEN NMT AND AXE
Bertil Thorngren stresses the similarities between NMT and AXE:
“Pretty well any attempt to make forecasts about new technological solutions are doomed to fail. There is quite simply nothing meaningful to compare with, especially because we basically know nothing about either demand (what customers want) or supply (what technology can permit at different times). So then you have to keep the doors open in both ¬directions.”
“If technology advances more slowly than expected, you may have to adopt a fallback option. If it moves more quickly than expected, you need scope to take full advantage of the new possibilities.”
A modular and scalable approach made this possible for both NMT and AXE. Virtually everything was there from the very beginning. For instance, there was scope for later upgrades with digital selectors in the AXE, and scope for increasingly advanced handover and roaming as the number of users grew – and with them the number of base stations – in NMT. This meant that, right from the start, there was scope to reap the benefits of continued technological developments.
This was how both NMT and AXE gained “future competitiveness.” The competitors were not as mature from the start, so it was not as obvious how they could scale up or benefit to the full from continued technological advances, Thorngren says.
“Both the NMT group and the people working with AXE at Ellemtel were unusually successful in getting this equation to work. In principle, the same solution remained reasonably intact throughout the dramatic growth in the number of users and radical improvements in technological performance. Hats off to their achievements.”
Author: Svenolof Karlsson & Anders Lugn