Tatango - Tatango is a mobile messaging platform for agencies.
Avochato - Text messaging for your business.
Postscript - Like Mailchimp for SMS
Flowroute - Flowroute provides direct access to telephony resources - such as calling, messaging (SMS & MMS), call routing, SIP Trunking and Communication APIs.
GetChat.App - Add WhatsApp chat to your website for free
Business Texting - Business Texting is an automated business messaging software that will allow your business to engage more customers and boost sales.