Which Betamax can I use?

[ambrose]

I've tried to set up Voxalot to use Smartvoip but can't get it to work (works with Blueface for me, so set up seems Ok).
Am getting more & more confused trawling the forums, and there is no mention of Smartvoip.
Before I set up more accounts and give money to Betamax!, could someone give me a pointer - are there some which work and others don't? Do they have to be on the providers list?

Thanks in advance,
Ambrose