4P4C RJ9/RJ10 to 3.5mm Female Headset Adapter Cable Stereo Converter f
Telephone Line Splitter Modular Adapter 4P4C | West Florida Components
RJ9 4P4C Telephone Handset Splitter Adapter Cable
Amazon.com: VoiceJoy RJ9 Headset Adapter Extension Cable- Female 4P4C to Male 4P4C Cable, not RJ11/RJ12, for Plantronics, Jabra, & Hot Desking Office Phones : Electronics