Thanks for your reply. Good idea to go direct to manufacturer. Happily, I don't have to pay anything either. I just need someone who is willing to work with Medicare.
I guess one can't swim with these things...oh well
But I do want to go to Europe with it. So I will ask the manufacturer for converter

I talked to someone from Inogen and they told me that G5 has been discontinued and new model now Rove 6. They said also that when one goes through Medicare one gets a refurbished model not above G3. I also asked if I buy the model, will Medicare cover the "maintenance" and they said no. But Medicare site says it does.
I learned long ago to not take the first answer and keep asking until I am satisfied!!!
Do you need oxygen at night? They suggested I could use the portable model for my night needs (I am waiting for test results). I am thinking that might consume the batteries faster so better to have a stationary concentrator if I need at night.
Also I wonder about servicing to be sure that the machine is continuing to perform correctly.
My prescription says something about evaluate to maintain oxygen% at 90. So I need someone to check it if I buy it. Whereas if I go through Medicare it is part of the contract obligation.

I got a surprise. My stationary oxygen concentrator provider also gave me a portable Inogen G5 through Medicare at no cost to me. They said they bill the same price to Medicare whether I keep the portable or not. I have no idea why. But I am beginning to think that Inogen is giving out these discontinued models to O2 providers, because patient needs batteries (like printer ink) and Inogen charges a lot for the battery! And Inogen has stated product has 8-year life. So that 8 years of needing to purchase battery is recurring revenue for them since impossible to use any other battery.

My provider gave me carrying case and extra tubing, and one standard battery, but said I would need to buy my next battery as they do not carry Inogen products. I called Inogen and they said Medicare does not cover replacement batteries after first one dies. Is that your experience? Standard battery is $400, good for 500 charges they say. But there is an upkeep cost to these things!