Have long been used to Onvoy/Inteliquent/Sinch, Peerless, Horizon IP, Commio, and so forth.
Now a new one---
Five9: "Call & Contact Center As A Service (CCaaS) Provider"
Not a new company, but now some junk calls are showing up listing them.
Their phone company operating number (OCN) is 598J.
And---they have just been BOUGHT BY ZOOM for SEVERAL BILLION DOLLARS.
Expect to see more of them. 🙁