Headset Buddy 3.5mm OMTP Smartphone Headset to RJ9/RJ10 Phone Adapter for Cisco ONLY (PH35-RJ9Cisco) Convert 3.5mm smartphone headset into single 4P4C RJ9/RJ10 Cisco handset jack Works great with Cisco VOIP office phones with a RJ9 headset jack Save money by buying Smartphone headsets to use with your office phone's headset jack Reduce clutter with single headset Does not work with Apple EarPods due to the 3.5mm being OMTP based instead of CTIA