Twilio
"Twilio is reinventing telecom by merging the worlds of cloud computing, web services and telecommunications. Twilio hosts a telephony infrastructure web service in the cloud, allowing web programmers to integrate phone calls and SMS messages into their applications. Twilio's simple, powerful API minimizes the learning curve required to build advanced, reliable communications applications, and its Pay-As-You-Go pricing model means customers pay for capacity only when they need it, not before.
The company is funded by Bessemer Venture Partners, Union Square Ventures, Founders Fund, Mitch Kapor and other prominent investors, and is headquartered in San Francisco, CA. "