Note:
After upgrading GXV34xx to firmware 1.0.3.4 or higher version, downgrading to firmware lower than 1.0.3.4 is not allowed.
GXV3450 1.0.3.33: Release Notes Download Firmware
GXV3470 1.0.3.32: Release Notes Download Firmware
GXV3480 1.0.3.32: Release Notes Download Firmware
HTTP Firmware upgrade path for BETA release is:
firmware.grandstream.com/BETA