What are some alternatives?
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Twilio - Brings voice and messaging to your web and mobile applications.
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Wire - Private & Secure Messenger
Bandwidth - Track your Wi-Fi hotspot usage. Zero configuration required. It just works.