Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
KrispCall - Virtual cloud phone system for business
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
CallHippo - Easy to use Phone System with World-Class Support
Plivo - Plivo simplifies your customer engagement.