I’m currently using budgetvoip, but look through the list when my balance runs out, and find one that has good rates for where I want to call. Some of them have desktop app support, if that’s something you want. I have used voipyo and telbo in the past, but I’ll switch if I find a different provider with better rates.
I use Mobile VoIP. It’s a wrapper for which you need a separate subscription from one of the many voip sites. Go to MobileVOIP.com you should see a list of such providers. You can set your own caller id or no caller id.
Delete your comment before they actually consider doing this