I have been using this headset for 3 days now. Initially I had some snap, crackle, pop sounds with my Siemens SX66 phone. I elected to call the manufacturer of the phone and they recommended upgrading the phone ROM. I followed their recommendation and while I still seem to have some crackling in the beginning of the conversation the headset seems to be doing a great job. People tell me they can hear me, better then ever and the sound level is quite good. Unfortunately I am not able to get more then 3 feet from my phone but I think this is a Siemens issue. As a side note Siemens is not stepping up to their responsibility as a manufacture and deny any more help with the phone. It is their belief that I may be able to use the Siemens headset with this phone with greater success, but they are not sure if I can return it if it does not work. Basic avoid buying Siemens at all cost if you care about quality or customer service.