Dropping of Calls

I receive calls from different number of MBD eg. +***, +***, +*** and many more that the phone ring less than 10 seconds then its dropped. What's written on the system leaves a person concern, because it has to do with your credit rating. Sometimes there is noise in the background if you answer in time. Never ask is it a convenient time to speak, because I am in a public place and consultant start with can I have your Initials and surname for security reasons.