http://developer.att.com

The AT&T Developer Program supports the AT&T API Platform, which exposes RESTful APIs and offers SDKs to ease development. The AT&T API Platform SDKs for Windows® allow you to easily integrate with Microsoft technologies to invoke AT&T APIs, including those for speech-to-text transcription, SMS, and MMS messaging. Samples and source code are provided to illustrate API usage. Developers can leverage these samples and quickly add their own logic to write complete, business-ready applications.