When I picked up my machine, the technician who showed me how to use it also gave me a schedule showing how often Medicare will pay for replacement of the various supplies.
Particularly at first, I tried different menu options on the DME's phone system until I was able to reach a live human in order to be sure that the specific type and sizes of mask, pillows, etc. on their list for me were what I was actually using.
This was particularly important for me because I've changed the type of nasal cushions and size of mask and wanted to double check that the change had stuck.
My DME also has an automated phone reorder system and online reorder system, but these did not give exact details on the type of cushions, etc. The DMD may have improved this recently, but I haven't tried it yet. I still like to talk to a live human in case I have any questions.
My DME was a local company purchased by Sleep Central. I think I'm still getting the local people on some of the phone numbers I have. I've been happy with the service for two years now.
How you decide to order may depend on how you like the systems your DME offers, and whether you change type of mask, etc. Hope it works out well for you!