No message calls

repeated calls lately  says  U of Wyo on ID  wanted to survey

Calls every Sunday night?  No messages

I've never answered this call, but they call between 6:30 and 8:30 pm and never leave a message. Has been going on weekly for a month.

Been getting lots of calls in the last 2 weeks, but never any voicemail. When I call back I either get a busy signal or it just rings forever until it turns into a busy signal.  Tonight I actually picked up and just listened.  It was a woman’s voice, and she just kept saying, “Hello? I hear somebody there. Hello?”  Never identified herself or why she was calling.