Finally, I had a success with all of your inputs!!
Neither Apple nor Airtel know the process & willingness to support customers, they blindly follow without understanding the problem.
I requested Apple tech team to inform Airtel about EID block issue, but they were continue to do their own SOP!!
After burning more than 70days with Apple tech support & Airtel customer care, I just wrote mail to Airtel that I'm going to migrate to other service provider & throw this iPhone16.....
Airtel responded that they will fix this problem within 24hours, indeed they fixed it within 4hrs.
Now I'm using eSIM on my new iPhone16....
Help came from community.....
I wish Apple to include this case study to train their tech team to avoid future issues to other customers...