Laila Ohlgren was employed at Televerket in 1956 to work on the rollout of the Swedish television network. In 1972, when she began working in the Televerket radio development department, she was the only female engineer there. She is remembered for coming up with the idea of first dialing the number before making the call.

As has been pointed out, one of the aims for NMT was that dialing was to work in more or less the same way as for a normal telephone. This meant picking up the handset and then dialing the number. The equipment needed to be familiar to people. But it was not working properly in the field trails: the connection kept breaking.

“It was taking at least 15 seconds to dial a number. During that time a building or a tree could get in the way, so you ended up in a radio shadow, which meant that not all the digits were getting through,” Ohlgren says.

At the beginning of June 1979, just before a decision was to be made about the NMT specifications for the test, Ohlgren got the idea of turning the process around. This broke one of the commandments, which stated that the dialing procedure must be the same as in the fixed network.

“But as each mobile telephone was going to have its own little microprocessor, you could let it store the numbers before it started the call. I thought it would make connections more reliable. You could also use the frequencies better because you did not have to use valuable capacity during the actual dialing,” she recalls.

A quick test with thousands of connections driving around Stockholm during the June Public holiday weekend gave enough statistics to see if this new solution worked. It did.

At the very last minute, before the system specifications were laid down, the numbering system reserved for NMT subscribers was changed from a five-digit one to six digits. After all, there was a possibility that all the five-digit numbers could be used up in the distant future.

KIDNAP ATTEMPT

One area not included in the work that Televerket and L.M. Ericsson jointly assigned to Ellemtel involved radio technology. Both held the opinion that technical limitations meant radio technology was never going to be of any serious commercial importance.

There was explicit criticism of the technological optimists in the NMT group. Mäkitalo says: “It was not that people at Ericsson were more conservative than others, but it was typical of the culture in the industry in those days for people to find it difficult to look ahead and make general predictions. They quite simply knew best.”

The scene was set for rivalry, and one event in particular aroused the anger of the NMT team, recalls Haug.

“In the summer of 1978, two of L.M. Ericsson’s people sent an abstract with a description of the NMT system to the International Switching Symposium, which made it look as if the system was an idea dreamed up by L.M. Ericsson. What the writers did not know was that I was on the review committee for ISS and so I saw the document. I had just become chairman of the NMT group and realized that I had to do what I could to stop this paper, above all because I wanted to avoid any chance of our Nordic members feeling that we in Sweden were favoring L.M. Ericsson.”

In his subordinate position, Haug could not take any action against L.M. Ericsson so he showed the abstract to Åsdal, who had after all initiated the NMT process. “As I expected, he hit the roof and wrote a very stiff letter to Åke Lundqvist. The paper for the ISS was withdrawn and my Nordic colleagues, who I felt had to be informed, were satisfied. I do not think L.M. Ericsson ever got to know how Åsdal had learnt about the matter.”

To resolve issues to some extent, Haug gave a presentation on the NMT system at a major ITU conference in Geneva in the autumn of 1979. This was the first time NMT had been described at a major conference and Haug believes that “it could have had some value for the reputation of the Nordic telecommunication agencies.”

The two L.M. Ericsson employees made a new attempt for the 1981 International Switching Symposium, with the same result. To counter any further ambitions of this kind, Åsdal made sure that Haug was able to describe the NMT system in L.M. Ericsson’s own journal, Ericsson Review 3/81, as being a cooperative project, not an L.M. Ericsson one.

Author: Svenolof Karlsson & Anders Lugn

LAILA OHLGREN

In the spring of 2009, Laila Ohlgren won the Swedish Polhem Prize, awarded for top technical innovation.Her idea – to dial the number first and then make the connection – gave NMT significantly more capacity. For operators, it meant an increase of around 25 percent in income for the same investment.

© Telefonaktiebolaget LM Ericsson and Centre for Business History

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