In the context of most of these PSAPs having already moved to VOIP, there isn't a coherent reason why these calls shouldn't go straight from the carrier originating the call to the PSAP, without middlemen like Centurylink standing by to misroute those calls.
I'm always interested in Chicago history, so I went looking, but couldn't find anything at, for example, https://www.nena.org/page/911overviewfacts . Do you know anywhere this history is written up?
> 1976 Chicago claims to have had "the first enhanced 911 system of any major city" in the United States.
… so I guess in
> > 911 is a creaky old system put in place by a Chicago mayor looking to score some points with the electorate.
you meant E911 (which, as the linked page points out, is a nebulously defined and variously implemented technology), not necessarily 911?