Mini SIP Audio Intercom• HD Audio/Video Linkage /Self-Diagnosis /Auto Provision• Dual SIP line, Dual SIP servers and Onvif• 1 ports delay output and 1 ports sensor short circuit input• Aluminum alloy housing, stability & reliability• Unlock door with DTMF, DTMF tones• Ethernet RJ45 port, POE• Wall mounting, Products Dimensions: 88*120*35 mm• Compact design, easy to embed into a bollardDP91-S: One touch button for emergency callingDP91-D: Two touch button for emergency callingDP91-MS: One