I have just started using Kiwilink VoIP and I have not had any trouble at all. I find their support desk reasonably personal and knowledgeable. I read an article on this website that did not pay any service to them so I thought I would add something positive in case other people thought about using them. As most of you know any issues with VoIP is the broadband connection and if you have a wireless connection this can be more realible than fixed line connection thereby improving the quailty of voip.
If I could afford a fibre connection I'm pretty damn sure that it would be as clear as crystal.