TextNow - TextNow is a mobile virtual network operator (MVNO) that provides a free phone service to users by using other cellular networks coverage.

OpenPhone - Simplest way to own a business phone number

Dingtone - Dingtone is a free call and texting application for making unlimited calls and text messages to any number at the moment registered in any part of the world by any cellular company.

Burner - Disposable phone numbers -- now with MMS photo support

TextMe - TextMe is a free calls and messaging application at both local and international levels.

Dialpad - Switch is a cloud-based phone system built for Google Apps users.