VXi 203365 OmniCord-V RJ9 Lower Cord with Universal Compatibility and Mic Gain Control for Connecting VXi V-QD Headsets to Compatible Phones Microphone booster and adapter in one cord. Three-position compatibility switch works with most phone types. Eight-position audio booster provides transmit amplification when needed. V-type QD cord for use with VXi V-style quick-disconnect headsets.