That's a question there is no good answer to. According to the highlights of telecom subscription data released by Telecom Regulatory Authority of India, there are 811.59 million wireless subscribers in India. But, the report goes on to say that there are only 573.97 million subscribers in the Visitor Location Register (VLR).
What's the difference? VLR is the database that stores information about users that are roaming into a particular network. A user can be present in only one VLR at any given point of time. Thus, this is a better approximation of the number of active users that are currently in the network.
This means 237.62 million subscriptions are dormant rather than active subscribers on the network. Also, many subscribers are using dual-sim handsets with more than one connection on the same device - which means the actual number of subscribers may be even lower than the 573.97 active subscriptions.
Note: This VLR data excludes the number of CDMA BSNL subscribers as the service provider did not provide the VLR details of their 5.57 million subscribers.