Who called from 4803600240

When I answer the phone there is no one on the line

Leaves voicemails that consist of the phone ringing

I just got a call from that number and no one was there they have called me about 3 times in 20 minutes and it's the same thing so they are now blocked

This number has called me 2 or 3 times a day for several weeks. They leave a message with a high pitched tone and no voice. Today the message said "This is Michelle" and then she hung up.

After I picked up the phone. they remained silent the whole time before hanging up.