Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
Plivo - Plivo simplifies your customer engagement.
Zoho Desk - Industry's first context-aware Helpdesk Software