Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
TractionGuest - Safe, secure workplace for all.
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Proxyclick - Connect with Confidence
Plivo - Plivo simplifies your customer engagement.
The Receptionist - The Receptionost is a visitor managemnt solution that has visitor logging system to track visitor traffic.