AT Command Tester is a web-based program to test AT commands on mobile devices. A variety of communication devices such as mobile phones, M2M modules, modems, fax devices supports AT commands for device control.
Please follow these guidelines to use the AT Command Tester,
Find COM Port
Device vendors generally provide software drivers for Windows OS. If the drivers for the device is already installed on the system, the COM port of the device can be found through the Device Manager->Ports. Choose the COM port accordingly from the drop down list in AT Command Tester program.
Set Port Speed
Baud rate in the AT Command Tester program should be set same as the baud rate of the device. For determining the baud of the device, please check here.