Who called from 9032002028

Unsolicited call on my mobile phone.  No one was there.

Multiple calls. When answered nobody was there. Obviously an automated troll to capture working phone numbers for telemarketers.

Automated message telling me I was the only person on the conference call. Nothing else

What happened after it says only person on the conference call?

Has called several times the past few days. I answered, a recorded voice said hello, then nothing else afterwards.