Bsnl is the indian governments telephone service provider including landlines and mobiles. They provide great 3G packs at very low cost and the speed of internet is actually quite great.
They also provide cheap calling plans and various packs which is very appreciable.
Overall the call quality, internet speed, network coverage is quite impressive.
The biggest advantage in using BSNL 3G is that it is very inexpensive and suits everyones pocket.