GPRS Device and Azure IOT Hub issue

_x000D_ _x000D_ We are developing a system in which several devices equipped with Simcom SIM800 GPRS modules need to send telemetry data to an IoT Hub at port 443 using the AT command for GET & POST data to Azure REST API endpoint. https://{IoTHubName}.azure-devices.net/devices/{deviceId}/messages/events?api-version={api-version} Problem: We got the message successfully at IOT end. But at device end we always got Status Code 600. Note: 1. We are able to Get & Post from any other REST Api using AT command, which we are host in Azure & able to get status code 200. 2. We call our own REST service via AT command, which is host in Azure, purpose of this service to post data into IOT Hub using azure C# SDK. We get status 200. 3. We can not use Azure C SDK due to device incompatibility. so we using IOT Hub Rest API call via AT command.