Airtel — Calls are not connecting even though I am in range

To whom it may concern,

I am gangadhar yelamali (Airtel mobile number: [protected]) from gadag, karnataka.
I have been using this number for almost 3 years and experiencing one or the other issues since then.
But, from the last few months, my customers are unable to reach me even though i am in very good network coverage. My entire family uses the same network, but no issues for them so far.
As i use this number for my business, i am afraid of losing my customers just because of this network issue.
I have informed airtel customer care several times regarding this. I have even changed my simcard once. But, still have got no solution to this issue.
Hence, i am requesting for the main reason for this issue and for the faster response from your side.
Regards,
Gangadhar yelamali