Oh I love discussing old tech, so I can’t help being pedantic on this topic!
The first paper describing a cellular telephone network was written in 1947 by an engineer at Bell Labs, but it was two decades later before Bell Labs worked on implementing anything, so it doesn’t really count as being “invented” in my opinion.
Maybe you can call MTA (Mobiltelefonisystem A) a “cellular network”, but it wasn’t “wide-spread”. It was developed by Ericsson starting in 1950, and entered commercial use in 1956 with 26 subscribers in Sweden. It operated until 1967 and never had more than 125 subscribers in two Swedish cities. The receiver equipment weighed 40 kilos and it used the car battery to power it. Yes, it had multiple cells, but an operator had to manually select the closest base station to connect incoming calls and you couldn’t switch a call from one cell area to another.
The first automatic “call handover” system was invented in 1970 by a Bell Labs engineer which allowed mobile phones to move through several cell areas during a single conversation without loss of conversation, but this wasn’t commercialized until December 1979 in Tokyo by NTT. The technology used by NTT was developed by Motorola in the early 1970s.
Most people would say that the first “wide-spread cellular network” was ARP (Autoradiopuhelin), which started service in 1971 in Finland, but it required operators to manually connect calls and there was no call handover between cell areas. The ARP network had 10,800 users in 1977 and it had 140 base stations in 1978. ARP was not fully automated until 1990.
In comparison, the first computer network was the military radar system Semi-Automatic Ground Environment (SAGE) that started operation in 1958 in Canada and the US and would connect 56 computers when completed. SAGE had its origins in tests in April 1951 that transmitted data from radar over telephone lines to a computer. A “Summer Study Group” of scientists in 1952 recommended the creation of “computerized air direction centers.”
The first commercial network was an airline reservation system, called Semi-automatic Business Research Environment (SABRE) in 1960 that connected mainframes. The first commercial modems were the Bell 103 by AT&T with full duplex transmission and a speed of 300 bits per second.
The first wide-spread computer network was ARPANET, which started its development in 1966 and it had a 4 node network functioning on the West Coast in December 1969. By March 1970, it had connected to Cambridge, Massachusetts on the East Coast. ARPANET was fully automated in late 1969 and had a directory. By the mid-1970s, ARPANET was a nation-wide network. In 1974, the TCP specification was created and that spec coined the term the “internet”.
I can’t find a good description of how the SAGE network operated so I’m not sure how advanced it was, but ARPANET in 1969 was a decade ahead of the first commercial fully-automated cellular network, which was owned by NTT and only covered Tokyo in 1979.