(314)492-5951 calls, no message, CID shows St. Louis, MO.   Variant of a collection agency that also leaves no message. On another site like this note that it should not be answered.  If you do have medical debt, contact your debtor and make arrangements through them - never talk to any callers who leave no message and don't identify themselves in caller-id.   There are plentyof frauds out there.  I pay my bills, but only to the people I owe the money too.