First, Unix and Erlang are not good examples here. They were more like tiny research projects that escaped the lab. No particular economies of scale needed. In

First, Unix and Erlang are not good examples here. They were more like tiny research projects that escaped the lab. No particular economies of scale needed. In comparison to that, te technical artifacts these companies were actually aiming to produce (e.g. networking equipment) had hundreds of times more people working on them. Second, Ericsson is not a telco, they're a supplier. Exactly the kind of entity that can achieve economics of scale on building say a mobile gateway router or a billing system, by building one that can be used by a hundred telcos, not just one. Vertical integration did make more sense for the AT&T of old. The market didn't yet exist, or wasn't standardized enough, for them to be able to depend on that.