Fonada Virtual Number - Avail of Fonada’s virtual number service to grow exponentially. Use virtual number for OTP verification to establish a secure business communication.

Twilio - Brings voice and messaging to your web and mobile applications.

Opt It - Opt It offers mobile messaging solutions to enable businesses to directly connect and communicate with customers. 

Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates

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)

Clockwork SMS - Clockwork is an Easy Text Message API. An SMS API for Developers. Build powerful apps and include SMS. Signup is free, Try it now.