RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
Twilio - Brings voice and messaging to your web and mobile applications.
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Nexys Mobile - Mobile Phone plans and Services for highly mobile small business workers and entrepreneurs who run their lives from their phone.
BulkSMS - SMS messaging service provider offering two-way SMS communication services.