TextNow - TextNow is a mobile virtual network operator (MVNO) that provides a free phone service to users by using other cellular networks coverage.
RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
Google Voice - Google Voice gives you one number for all your phones, voicemail organized in an email format, free...
Burner - Disposable phone numbers -- now with MMS photo support
Phonebooth - Phonebooth is one of the leading voip providers, providing phone systems & phone service for small businesses.
Eir SIP Voice - eir SIP Voice is revolutionizing the core communications tool of business that carries both calls and data over just one connection.