The IMEI (International Mobile Equipment Identity) is a 15 digit number unique to every mobile phone and 3G modem. It's used to identify devices and can be used to prevent them from working if reported stolen.
The majority of 3G modems have this number printed on the back. Some modems have the IMEI number hidden in the SIM card compartment.
If you are unable to find your dongle IMEI number, please watch this YouTube video, showing how to find the IMEI number using Windows.
