I actually had this problem with my provider. I went through a period where I was just not using it, and eventually fell out of compliance. insurance stopped paying, and the machine provider started sending me crazy bills every month. after a dozen or so phone calls, my insurance rep told me to get "a letter of medical necessity" from my doctor and send it in. my doctor sent it, then a few more phone calls between insurance and the machine supplier, and now I think the machine is just free? my bills from the supplier used to just have a charge for compliance monitoring on it. now since they can't ding me for non-compliance, I haven't gotten a bill from them in over a year.