The Mk4 Alarm Autodialler from the 1960’s!
Notice the Reel to Reel Tapes on top and the Internal Valves.
This Early Autodialler certainly did not connect to the GSM Networks, this was a pure PSTN machine with Pulse / loop disconnect dialling.
We still have one in our showroom purring away!
Written by M60 GSM Alarm Dialer