Releans - Communication platform for Messaging and Chatbots
Jasmin SMS Gateway - Jasmin is a very complete open source SMS Gateway with many enterprise-class features such as:
Twilio - Brings voice and messaging to your web and mobile applications.
Ozeki NG SMS Gateway - Ozeki NG SMS Gateway is a powerful, reliable and flexible SMS Gateway application.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Bulk SMS Services - Sending Bulk SMS to the customers will engage the customers with your business and new offers.