I hope you can help as i have submitted numerous tickets to yeastar with no response whatsoever. I recently upgraded a U100 from 22.214.171.124-8 to 126.96.36.199 which i downloaded from http://www.yeastar.com/Downloads/IP-Phone-System-Firmware . This upgrade however made it impossible to create trunks and did not recognize my TA410 gateways so i decided to downgrade. So looking around i could not find any link to download 188.8.131.52-8 firmware i went with the 184.108.40.206 to downgrade but it stays stuck in 220.127.116.11
*I upgraded the firmware in the first place because TA410 gateways were recognized but were not configurable from the TA provisioning menu.