4000 GROUPS BLACKLIST: Caller ID box has 4000 groups of large capacity blacklist storage, blocking all nuisance calls. | LCD SCREEN DISPLAY: Call blocker uses LCD screen display for easy operation and simple But tons for easy operation. | PLUG AND PLAY: Call blocking device is designed with dual plugs, plug and play, suitable for most landline phones. | ANTI HARASSMENT: Call blocker can block nuisance calls, super filtering anti harassment, guarding private pure space. | EASY TO USE: Phone blocker is easy to use, just press the block But ton to block incoming calls permanently.