Surfing the Internet, e-mailing and faxing have become routine daily activities. Therefore, it is becoming more and more important for your telephone line connection to be fast, clear, protected and uninterrupted. Outside noise such as electromagnetic waves from various radio devices and instruments could decrease your modem/fax transmission speed and interrupt your Internet connection or telephone conversation. The TelCheck Pro provides a sophisticated noise filter to improve your line connection. It is also equipped with a surge protector to protect your modem/fax/telephone from dangerous accidental power surges. In addition, it was also designed with a circuit that protects your connection from interruption by other telephone stations. With the TelCheck Pro, you can relax knowing that virtually nothing can come between you and the Information Superhighway. Connector: Input: RJ11 6p4c Jack. Output: RJ11 6p4c Jack. Quickly check if the line is analog signal. Easy to identify the polarity of the line. Tells you if the line is overcurrent. Prevents your modem from damaged by plugging in incorrect telephone system. Easy to identify the connecting status of the line wheter it is a new installed line or an existing line. Compact and easy operation. Line noise filter reduces RFI interfering.