You work for a firm that gives its employees with dozens of the same smartphone model. You call the provider's tech support number for help while debugging one smartphone that won't connect to the...

You work for a firm that gives its employees with dozens of the same smartphone model. You call the provider's tech support number for help while debugging one smartphone that won't connect to the cellular network. The technician requests the device's IMEI number. What is it that she is attempting to figure out? What is the significance of this?