Upgrade of firmware is of own risk.
 
This version only for Suncomm SC-375 Version hardware PCB mark: 2N149A , GSM 900/1800

Check your PCB mark, entering your gateway and select Update New Firmware. 
This will show the existing PCB mark.

If in any doubt please contact your re-seller.

The new FW will fix known bugs in version v6.693m and above (check info in your gateway)

After upgrade the fw version will show v6.693o

Do not unzip the file, just uload as is.