Jasmin SMS Gateway - Jasmin is a very complete open source SMS Gateway with many enterprise-class features such as:
Bulk SMS Services - Sending Bulk SMS to the customers will engage the customers with your business and new offers.
Ozeki NG SMS Gateway - Ozeki NG SMS Gateway is a powerful, reliable and flexible SMS Gateway application.
MyTask - MyTask is a centralized platform designed for office management, invoice management, and work management that allows a business to have the required service agility.
BudgetSMS.net - Cheap SMS Gateway with simple HTTP API to send SMS messages worldwide.
KAPSYSTEM - KAP Computer Solutions Pvt. Ltd.,