Yes, by law vendors who provide oxygen need to provide refilled tanks, i believe these called e-tanks.

Ionogen is not covered by insurance, you paid out of pocket. Once primary or pulm md writes prescription for o2, vendor who supplies who supplies would send concentrator with easy fill system and etanks to fill. By law they also need to provide metal stand for e-tanks in case of earthquake as tanks need to be stored in upright position.
If you have medicare, go through ther patient phone line.