Google Voice - Google Voice gives you one number for all your phones, voicemail organized in an email format, free...
RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
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.
Talkatone - Android App on. Google Play. Stop paying for cell minutes, texts & landlines; Turn your iPad or iPod touch into a phone; Call/Text even in areas with bad cell coverage; Call/Text when travelling without paying for expensive international minutes.
Nexys Mobile - Mobile Phone plans and Services for highly mobile small business workers and entrepreneurs who run their lives from their phone.