called my cell today, left no message

When I answered the call the caller hung up and I tried several times calling the number back and it goes to voice mail each time I call back.   I also got the call on my cell phone.  I thought that it might had been somebody that I knew, that is the reason for me calling the number back.  I also thought that I did not answer the phone in time and that is why the caller hung up.  But it did not seem right that every time I call the number back I get no answer back and I go right to voice mail.

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Called my phone about 30 minutes ago 9:56am.  Thought it was someone I knew so I answered and they hung up on me.

Called. Did not answer. No message.