YouMail - YouMail turns visual voicemail into a personal assistant for handling all your missed calls.
OpenPhone - Simplest way to own a business phone number
MightyCall - Virtual phone system that lets you run your business from anywhere.
Burner - Disposable phone numbers -- now with MMS photo support
Grasshopper - Grasshopper enables entrepreneurs to build a virtual office that connects callers to employees, wherever they are.
TextNow - TextNow is a mobile virtual network operator (MVNO) that provides a free phone service to users by using other cellular networks coverage.