Should I replace my old alarm panel or the entire security system?

Replace only the panel when the existing cables and detectors are reliable and compatible. Replace the full system when wiring is damaged, detectors fail testing, zones are poorly documented, or the old layout no longer protects the property. A professional assessment evaluates each cable, sensor, siren, communication path, and risk area — and in most retrofits the practical answer is a hybrid: reuse the proven wired components, add modern Ajax devices where coverage or functionality falls short.