The mobile Subscriber base in India at the end of Nov-2011 has reached 880 Mn [GSM + CDMa] combined.

Here is how operators rank against each other in subscriber base,

Airtel 174.7 Mn
Reliance 149.1
Vodafone 146.8
Idea 104.0
BSNL 92.1
Tata DoCoMo 83.4
All Others 130.1