If I had to guess, my bet would be that the gate equipment is sending low on-hook voltage, probably only 24 volts or less. So go to the OBi110's web portal (NOT the OBiTALK portal, but rather the device's web browser - you may need to dial * * * 1 to get the IP address), then expand "Status" in the left-hand menu and go to "PHONE & LINE Status", and see what voltage the Line Port Status shows when the line is connected and the phone is disconnected (or on hook). If it's less than 25 volts, that's the problem. The LineInUseVoltageThreshold and LineInUseCurrentThreshold can be adjusted under the Physical Interfaces, Line Port settings (on either the device or by using the Expert mode of the OBiTALK portal - if you use the OBiTALK portal to configure your device then you will have to make the change there, or it won't "keep").