Telecommunications: Do VoIP phone number still live on Class 5 switches?

I read something recently that suggested that phone numbers of VoIP providers are still actually owned by a LEC, and that they would be routed to the relevant Class 5 switch before being handed off to the VoIP provider's network. Is that true? Like if I call an AT&T VoIP number from the PSTN, it would have to be routed to a local Class 5 TDM switch before being handed off to AT&T's VoIP network? Seems ridiculous. I always thought that VoIP carriers essentially had "virtual" Class 5 switches (made of Broadsoft servers and such) that would interconnect with like a Class 3 switch or something for PSTN connectivity.