Continuously calls and leaves no message.

Got a call Sunday at noon.
Didn't know the number so I didn't answer.
They left no message

This is apparently one of several extensions calling out from a behavioral health center located in Indiana. (317) 621-xxxx numbers have been calling me for a few months but when people realize they have the wrong number, they hang up. The last time I answered, someone mumbled "Hello who is this" and then hung up, but then I was transferred to the voice mail of someone named "Wendy." I left a message before realized this was another call from that ward. I don't know how someone there got my number, but there's really no way to get them to stop.