The D-Link DVX-2020 is a 4-port FXO expansion module designed specifically for the D-Link DVX-2005F IP PBX system. This module allows businesses to connect up to four analog telephone lines (PSTN) or traditional PBX extensions to their DVX-2005F system, expanding voice connectivity options. It provides a reliable and seamless integration, ensuring high-quality voice communication and enhanced flexibility for your communication infrastructure.