Phony back brace scam, probably. Left no message. When called back, a recording starts right out saying, "If you would like to have your number removed from the call back list ..." I just hung up since no normal caller has such a recording.
Don NOT answer calls from this number or from any number with which you are not familiar. This is another Medicare scam trying to sell you a back brace. Where they got the number is anyone's guess, perhaps from the government.