A:AnswerKeith - We are sorry to hear that you are having issues registering your IS6200 cordless headset on your DS6752-4. However, the IS6200 is not compatible with the said phone system. This cordless headset will work with some of the DECT 6.0 phones, the DS6291 or DS6722 to name a few.
Thank you,
-VTech Support
A:AnswerDave - we're sorry but the IS6200 will not work with the CS6124. Some of the models compatible with the cordless headset are CS6929, DS6421-3, and LS6425-2. Thank you for your interest!
A:AnswerYes, you can connect it to the headset. It works very well. Your iPhone will also connect. You can have 2 blue tooth devices so the headset and iPhone will do it.