Kannel - Open Source WAP and SMS Gateway
Ozeki NG SMS Gateway - Ozeki NG SMS Gateway is a powerful, reliable and flexible SMS Gateway application.
KAPSYSTEM - KAP Computer Solutions Pvt. Ltd.,
BudgetSMS.net - Cheap SMS Gateway with simple HTTP API to send SMS messages worldwide.
Power SMPP - Enterprise grade messaging software
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.