There were no "portable telephones" in '70-'72, at least in the sense we know them today. (wireless telephone)
What did exist at that time however were portable transceivers (contraction of transmitter/receiver), the older version of the walkie-talkie, a two-way AM
The period saw also the transition from "all tube" (vacuum tube or valves) to hybrids (tubes + transistors).
Some (purely radio) networks had the ability to "patch" the radio to the (conventional - wired) telephone network, through a device called "phone patch" or "phone interconnect". It was still two-way, one talks / one listens.
The first such (trans)portable radios were often called "lunchboxes".