LG Nexus 4 compatibility Airtel India
Yes, it will be compatible. Google has already mentioned that it will be compatible with over 200 networks worldwide. That includes Airtel India as well.

I have bunch of friends who are using Galaxy Nexus in India. Voice calls and 3G/2G works smoothly. The same should be true about Nexus 4 as it is also an unlocked device like the Galaxy Nexus.