VoIP <--> PSTN provider recommendations

[VirginSnow at vfemail.net]

Okay, folks... once again, it's time for one of those "tell me your
favorite..." questions!

I'm shopping for a new VoIP <--> PSTN service provider (so I can place
and receive telephone calls over the Internet).

Does anyone have experience with good providers?  Any providers
(besides NuFone) I should steer clear of?

Note: Providers which charge monthly fees go at the bottom of my list.
I just don't talk that much. :) If I had a choice of paying a monthly
fee for good-quality VoIP service or getting shoddy service with no
monthly fee, nine times out of ten I'd take the latter.

So, suggestions, anyone?