I've had a quick play with PennyTel and agree they are very good, their pricing is also pretty sharp.

One other provider also worth looking at is bbpglobal, they are one of the few providers that will let you sign up multiple DID's to the same account so for example you can have an Auckland number and a Sydney number on a single account which means you only need to use 1 port of your PAP2/WAG54G for both and wouldn't actually need VFX account at all.

The beauty of VoIP is that you aren't tied to a single provider.