The original replacement headset for CS10 and CA10 has been discontinued. This over-the-head, headband style headset is an alternative. It is the Plantronics M214C headset with noise canceling microphone and inline volume/mute control on cord. The cord comes down to the 2.5mm plug that goes into the remote control belt pack of your Plantronics CA10, CS10, CT10, CA10CD, CT12, CT11, CT14 and Avaya LKA10 or Avaya 10U100. The headset is covered by 1 year factory warranty.