Update 09-October-2014
How to OTA update ? (Go to settings>About>System Update>Check for Update)
How to update Manual ? Here
How to update via ADB sideload ? Here
Zenfone 5 T00F WW(Required 2.19.4
http://fota.asus.com/
Zenfone 5 T00F TW(Required 2.19.4
http://fota.asus.com/delta_package/phone/WW_a500cg/formal/WW_user_2.19.40.6_20140927_8163-user-WW_a500cg-WW_user_2.19.40.18_20141003_8008-user-WW_a500cg-20141003/WW_500_0927_1003_20141003.zip
Zenfone 5 T00J WW(Required 2.19.4
http://fota.asus.com/delta_package/phone/WW_a501cg/formal/WW_user_2.19.40.6_20140927_8163-user-WW_a501cg-WW_user_2.19.40.18_20141003_8008-user-WW_a501cg-20141003/WW_501_0927_1003_20141003.zip
Zenfone 5 T00J TW(Required 2.19.4
http://fota.asus.com/delta_package/phone/TW_a501cg/formal/TW_user_2.19.40.6_20140925_5363-user-TW_a501cg-TW_user_2.19.40.18_20141003_8008-user-TW_a501cg-20141003/TW_501_0925_1003_20141003.zip
Zenfone 6 T00G WW(Required 2.19.
http://fota.asus.com/
Zenfone 6 T00G TW(Required 2.19.
http://fota.asus.com/delta_package/phone/TW_a600cg/formal/TW_user_2.19.40.13_20140925_2331-user-TW_a600cg-TW_user_2.19.40.18_20141003_8076-user-TW_a600cg-20141003/TW_600_0925_1003_20141003.zip
FULL FIRMWARE HERE