Microsoft Azure IoT Hub S3 addresses enterprise scenarios where you have a large number of devices that generate large amounts of data and must transmit messages frequently. Each unit of the S3 edition lets you transmit up to 300 million messages per day.
Azure IoT Hub S3 is the fourth edition in the Azure IoT Hub family. The others are Free, S1, and S2.
For more information, please visit the Azure IoT Hub page. For more information about pricing, please visit the Azure IoT Hub pricing page.