In the old days it was relatively easy to determine what devices were connected to the corporate network; they were large and cumbersome. Indeed, it was difficult for new devices to be connected to the network without the assistance of the corporate IT department; the confusing array of IP addresses and ports and the obscure art of modem configuration meant that it was well beyond most of us to do this.
For those who did require remote access, a pair of dedicated modems was needed and a telephone line which would remain stable and undropped for hours. I remember needing a line to remain connected for 7 hours, knowing that a click on the line meant that we would have to start again. Access to the network from outside could only be achieved through modems so, to ensure the integrity of the network, all that needed to be done was to check that there were no unexpected modems connected to phone sockets in the building.
If users were to be allowed mobile devices, these were in general confined to senior staff – none of whom could ever work out how to circumvent the controls. Mobile phones were just phones which were cordless. The IT department had total control over the devices used, what software was on them (if any) and nothing which was not IT controlled was allowed to access the network. Few users worked, or were expected to work, remotely.
Oh, how it has all changed!