EZ Texting - EZ Texting provides SMS marketing solutions to businesses of all sizes.
Twilio - Brings voice and messaging to your web and mobile applications.
Textmagic - The all-in-one solution for all your business texting needs - marketing campaigns, two-way SMS chats, reminders, notifications, and internal staff communication.
Bandwidth - Bandwidth offers SIP trunking, Emergency communications, and Voice & Messaging APIs.
SimpleTexting - SimpleTexting offers SMS and text marketing services for companies of all sizes.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates