The document provides instructions and code samples for sending SMS messages using the Inforu SMS Gateway API in 3 sentences:
It describes the HTTP POST interface for sending SMS messages with XML requests, including simple and advanced XML examples and describes the response XML structure. Code samples are provided in C#, PHP, and VB for sending SMS messages by constructing an XML request and posting it to the API URL. The document also covers additional features like sending messages at a later time, delivery notifications, and receiving SMS.