Line2 - Line2 adds a second phone number or complete cloud business phone system to smartphones & computers that's robust yet affordable. Buy online or get a custom quote.
RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
Phone.com - VOIP Business Phone Service + Virtual PBX
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
Nexys Mobile - Mobile Phone plans and Services for highly mobile small business workers and entrepreneurs who run their lives from their phone.
FreePBX Hosting - Cloud-hosted, commercially-supported version of FreePBX