Airtel — Fraudulent call from unknown Number of Neighboring Country

Address:

North 24 Parganas, West Bengal

Today I received a call from [protected]. I missed the call ,and in turn when I called back,could not reach it and it was playing some customised messages form that service provider .What stuck me was that it contained lots o[censored]rdu/ arabic terms, I got suspicious and when I searched over internet, i found that Its a number from Pakistan.Now I want to know how is my number going available overseas to some other neighboring country , and what steps should airtel as a service provider take to ensure the privacy of the numbers of its customers and steps to be taken by airtel to stop these fraudulent calls from reaching Indian citizens?

Thanks..