SIP Talkback Door Intercom allows communication to SIP-based telephone systems or Valcom Enhanced Station Port adapters via an IP-based network- Mounts In Standard Double Gang Electric Box- High Loudspeaker Levels for Use in Moderate to High Noise Areas- Indoor Only- Smart Relay VM-SRLY for VIP-176A- RJ-45 for network connection- 1 Form C Smart Relay optional- Network activity LEDs- Power over Ethernet PoE 802.3af compatible