They called me I ansewered , they hung up ? I keep calling back the phone is busy. LOL just courious

Why do I receive calls, and you listen and hang up ? Calls are around always 9-10 am.

I received multiple calls from this number.  I did not answer, and they left no messages.  This is the Davis/Woodland/Dixon area code.  It seemed strange so I looked them up.  I do not think I will answer after reading this! thanks.