called then hung up

Called me; couldn't understand them; asked for a supervisor because they were from India and I couldn't understand them; hung up.  I tried calling back and the message was "Hello?, Hello?, Hello?, GOTCHA!  

they have called and hang up when we answer

Received a call this morning from this number and the gentleman on the other end was very difficult to understand.  I was able to have conversation with him and he was conducting a "health survey".  Questions were relative to allergies/asthma, pets in home, smokers in home, and brand of vacuum owned.  After such questions were answered, he proceeded to ask the ages of the adults in the home, I told him that was unnecessary information and I began to ask him questions about the survey.  I asked why this survey was being conducted and who he was performing the survey for.  His first response was for a company and then he changed it to a school.  I asked which school and he told me Harvard.  I told him that I was not believing him and he quickly ended the call.  I tried to call the number back and got a voicemail that sounded like somebody answering a phone...hello, hello.  I did a reverse number look up and all I can come up with is a landline in Sedalia, CO???