Which statement about using DSL with alarm systems is correct?

• A. A DSL filter near or in the panel
• B. DSL filters are not needed with alarm systems
• C. A DSL filter must be installed at the service entrance
• D. DSL cannot be used with alarm systems

Answer: (A)

DSL uses higher-frequency signals on the same copper line as voice, and a monitored alarm dialer sends signals over that line to the monitoring center. Without filtering, those DSL frequencies can couple into the alarm circuit, causing garbled signals, missed alerts, or false alarms. Installing a DSL filter right at the alarm panel or just before its connection ensures the dialer operates on a clean, filtered line. This local placement protects the critical communication path even if other devices on the line generate DSL noise. Filtering at the service entrance alone isn’t as reliable because wiring paths can still expose the panel to DSL noise, and the idea that DSL isn’t usable or isn’t needed isn’t correct. Placing the filter near or in the panel allows DSL and alarm systems to coexist without compromising signaling.