GSC3610/3615/3620 1.0.7.5: for GSC3510/3515 HW 1.0D and all GSC3620
Release Notes Download Firmware
GSC3610/3615/3620 1.0.3.8: for GSC3510/3515 HW 1.0A, 1.0B and 1.0C
Release Notes Download Firmware
HTTP Firmware upgrade path for BETA release is:
firmware.grandstream.com/BETA