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)

Jasmin SMS Gateway - Jasmin is a very complete open source SMS Gateway with many enterprise-class features such as:

Clickatell - Simple, reliable mobile messaging cloud.

Kannel - Open Source WAP and SMS Gateway

ProTexting - ProTexting offers mobile marketing tools for businesses to communicate with their audience via SMS & MMS campaigns.

Ozeki NG SMS Gateway - Ozeki NG SMS Gateway is a powerful, reliable and flexible SMS Gateway application.