The design of i31S IP Video Door phone are based on experience and knowledge of Fanvil IP phone development. i31S are using standard IP/RTP/RTSP protocol for voice transmission and enjoy the advantages of full range of compatibility. i31S have a variety of enterprise‐level features and compatible with lots of major platforms, such as 3CX, Asterisk, Broadsoft, Elastix, etc. The i31S IP Video door phone is designed for operation in outdoor conditions. The robust mechanical construction offers protective coverage rating against dust and water (IP65). The i31S is economical devices with triple function(All in 1)‐ Access control by call, code and RFID card.