If recollection serves, we used the terms to make a distinction, since both networks were "public." To our discussions, PS meant packet-switched while CS meant circuit-switched. The data transport was what concerned us, and those were different, though both had to be framed in accordance with the requirements of the "CSTN" which was, in fact, not at all circuit-switched, physically. The term POTS, in common usage, was a reference to the current-loop circuitry presented at the end-user's pulse-compatible telephone.

It's easy to see how one could become confused between usages. Over time, the description has focused more on where the signal was digitized. With POTS, it was done at the PABX or at the CO. More modern systems do it at the end-user instrument, particularly since the system is, more and more, becoming a data network.

The transport mechanism, whether wired, or RF, is becoming transparent. Eventually, when the U.S. telecom monopolies finally get around to implementing the fiber-access network that the taxpayers (foolishly) paid in full for over a decade ago, it will really be a data network, with TV, voice, and data comm's all integrated over a truly high-speed (many tens of Gbps per end-user station) system. That may, in fact, make it possible to implement a fault-free RF telephone system, unlike the rubbish that's being so widely used for cellular traffic today.

RE