Currently telecom is all IP based. Telcos have a circuit switched system at the last mile for backward compatibility and profit reasons, but from your local CO to the terminating call CO is IP based. The telcos also own the internet connections as a tier one providers, so most of it is privately routed.
But yeah, the circuit switched system still exists only for backward compat. for the existing system. Cost for call routing has gone down significantly for telcos ever since the 1990s. (Some shithole countries do not apply.)
But yeah, the circuit switched system still exists only for backward compat. for the existing system. Cost for call routing has gone down significantly for telcos ever since the 1990s. (Some shithole countries do not apply.)