get_equipment_identifier
Description:
Gets the identity of the Modem.
This will be the IMEI number for GSM devices and the hex-format ESN/MEID for CDMA devices.
Warning: 
      
        
    
    The returned value is only valid until the property changes so it is only safe to use this function on the thread where this was constructed. Use dup_equipment_identifier if on another thread.
Parameters:
| this | A Modem. | 
Returns:
| The equipment identifier, or  |