http://fm.htek.com/rs/htek_2.0.4.4.58_20180913.zip
Firmware link:
www.htek.com/upfile/File/201901/30/Htek_UC862_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC860_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC842_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC840_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC806_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC804_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC803_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC802_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC926_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC926E_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC924E_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC924_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC923_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/31/Htek_UC903_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC912E_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC912_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC912G_Firmware_2.0.4.6.15.zip
www.htek.com/upfile/File/201901/30/Htek_UC902_Firmware_2.0.4.6.15.zip
Firmware Release Note:
www.htek.com/upfile/File/201901/30/Htek_IP_phones_Release_Notes_of_Version_V4_4_58V2.0.4.6.15.pdf