Airtel — unknown source calls

Address:

Faridabad, Haryana, 121007

Recently i have been getting calls from some unknown source. On the screen of my phone the caller information was displayed as "private number". Even the software "true caller" was not able to identify it or block it. When i went to airtel store for the same, they told me that some higher authorities like cbi or raw are calling you for confirming some details. I was also told that there is no issue in picking up the call. I want to know that if i pick up the call in future, and something happens, will airtel be responsible for the same or not?