I think of the difference more as a Kuhnian paradigm shift, rather than than as clan warfare. The whole value chain changed. PSTN is a highly fragile, highly s

I think of the difference more as a Kuhnian paradigm shift, rather than than as clan warfare. The whole value chain changed. PSTN is a highly fragile, highly standardized, high expertise technology that was possible using very rudimentary but custom hardware. IP telephony is essentially a repurposing of commodity IP connectivity, that uses modern commodity hardware (highly complex but well encapsulated) and requires a fraction of the personnel with a lot less years of expertise to work.