Airtel Postpaid Mobile Connection
Flash message during incoming and outgoing calls

I used mobile portability and switched from aircel to airtel. Often am getting a flash message that "Ciphering not provided by operator, insecure operation", when ever am on call (incoming and outcoming). Why am I getting this alert? I contacted customer care, they said there might be some problem with my mobile. But am gettin this alert from the day I switched to airtel. The problem is not in my mobile.

Kindly do the needful to solve this issue.