Most of the calls I receive are from human callers. So when they call and it's not for me or I'm not interested in their services, I'll just keep the phone asid

Most of the calls I receive are from human callers. So when they call and it's not for me or I'm not interested in their services, I'll just keep the phone aside and let the person talk for a while. Within a few seconds, he realises there is no sound from the other side. He does "hello, hello" multiple times and hungs up. Calls again. Again, "hello hello; Are you able to hear me?". This is very frustrating for the caller and he never calls me back or most of the time, they delete my number from the databse.