Moved to dial9 after a shocking experience with Vonage. Really great so far, with good comms. The only thing I'd criticise is that there is a certain base level of knowledge about VoIP/SIP required to set up your devices. Most companies wouldn't find this problematic, but for sole traders a better help section for the equipment that they sell/provide would be appreciated. That said, I've got no plans on moving away from them any time soon.