Excelsus Z-Blocker Z-330P2J Single-Line DSL Filter Filters one or more phone devices sharing a single jack Blocks DSL/HPN signals from phone equipment to enhance voice-band signal Isolates DSL/HPN from phone equipment impedance for peak data performance Ideal for blocking RF interference from DSL/HPN for uninterrupted data streaming Supports all major xDSL standards including VDSL; plus V.90, Caller ID and metallic-loop testing compatible