Indian govt is a very authoritarian system. which puts dictatorial legislations on internet communities and other cyber services including voip..
Voip is internet for telecommuications. which is the base of our internet usage. to interact and to use internet for various digital transactions. Including electronic money tranfers over the border.
Govt is worried that voip calls on numbers will ruin its revenue shares from the current gsm cdma system where the telecommunications biggies give their crores to the govt through both proper and improper channels so as to discourage the whole idea of voip.
voip uses digital voice protocol of machine to machine communication over the internet. which is done by using high speed interact(which is lacking in our infrastructure) and also reliable hardware(which we lack). the combination of these two important features turns out too profitable to businesses and inviduals all over the world except India.