Jasmin SMS Gateway - Jasmin is a very complete open source SMS Gateway with many enterprise-class features such as:
SuperPhone - SuperPhone serves as an intelligent inbox for SMS that filters, organizes, segments, and automates messages over SMS and Facebook Messenger.
Kannel - Open Source WAP and SMS Gateway
ShoutOUT - All in one business texting tool to send personalized alerts, promotions, reminders, short links and marketing campaigns, for any SMEs (hotels, restaurants, education, non profits, Woocommerce, banks, healthcare, agencies, supermarkets, weddings)
Ozeki NG SMS Gateway - Ozeki NG SMS Gateway is a powerful, reliable and flexible SMS Gateway application.
Textmunication - Get our SMS Marketing software to expand customer reach, increase traffic, generate leads. Easy to use bulk SMS software designed for gyms, churches, clubs.