What are some alternatives?
When comparing Vitelity and Google Voice, you can also consider the following products
Eir SIP Voice - eir SIP Voice is revolutionizing the core communications tool of business that carries both calls and data over just one connection.
RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
BVoIP - BVoIP allows to easily add Cloud & On-Premise VoIP PBX to the product offering without having to re-invent the wheel or add another layer to the daily operations..
Viber - Free and secure calls and messages to anyone, anywhere. Keep your conversations going no matter where you are.
Phonebooth - Phonebooth is one of the leading voip providers, providing phone systems & phone service for small businesses.
UberConference - UberConference provides a rich visual interface for conference calls. Simple, visual, and free to use, it's audio conferencing done right.