From what I understand (not legal advice) the FCC does not require resellers to register. It is the termination service that is required to register... VoIPo.
As far as taxes, your state's public utility commission is the determing body for that.

I'm just thankful that "Timo's" team is so responsive.... when I post questions/issue in the correct place! LOL

The last termination company I was with would take nearly a week to respond. I was unable to keep any customers!

In case you don't hear it enough, THANKS to Team VoIPo! or should I say Team Timo!