CallTrackingMetrics - Know who is calling and how they found you. Maximize the return on your advertising.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
CallFire - Grow your business with virtual phone numbers, IVR, voice broadcasting, mass text messaging services and power dialing.
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Invoca - Call tracking & analytics software
Plivo - Plivo simplifies your customer engagement.