Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
letsBrik - A Skype Alternative that is entirely web browser based.
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Amivox - Would you like to make international calls either free or at local rates ?
Plivo - Plivo simplifies your customer engagement.
KeepCalling - Best Rates for International Calls. No Contract, Expiry, or PIN. Use Any Phone, Smartphone or PC.