Discontinued
Product Part Number:  CA299-SP 
It allows you to connect the RS-232 port of two remote devices for fast and easy file transfers and data sharing up to 800-Meters (2,624 ft.) using  either 4 wire (for Full Duplex) or 2 wire (for Simplex) telephone line. It works as a null modem or line driver with DCE/DTE/Loop Back selectable, provides 1,500VAC lighting surge protection and  excellent noise rejection through the use of differential circuitry. This non-powered extender  supports transfer rates up to 19,200bps with full duplex & simplex modes. (Connectors: DB25 Female with 4 Wire Terminal Block & RJ11 Female)