Twilio - Brings voice and messaging to your web and mobile applications.
Melrose Labs SMSC Simulator - SMPP SMSC simulator to test SMS messaging applications.
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Sinch - Sinch is a powerful voice and messaging SDK that lets you bring your apps to life with VoIP and...
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Plivo - Plivo simplifies your customer engagement.