The country's telecom subscriber base fell by over 13 million to 921.47 million at the end of November 2012 due to "large-scale disconnection by operators".
The user base stood at 935.18 million at the end of October 2012.
All the operators lost users in November 2012, barring Reliance Communications, Loop and HFCL, which added a total 1,35,519 new subscribers.
"The number of telephone subscribers in India decreased to 921.47 million at the end of November, 2012 from 935.18 million at the end of October 2012, thereby registering a monthly growth rate of -1.47 per cent," Telecom Regulatory Authority of India (Trai) said in a statement.
Total wireless subscriber or mobile phone user base declined by 1.51 per cent to 890.60 million at the end of November 2012 from 904.23 million at the end of October 2012.
Trai attributed the decline in subscriber base "to large scale disconnection by some of the service providers."
Tata Teleservices lost 4.23 million users, the maximum among players to take its user base to 72.51 million at the end of November followed by market leader Bharti Airtel, which lost 2.80 million users and its user base now stands at 183.61 million users.
Vodafone lost 2.38 million users to take its subscriber base to 150.76 users at the end of November 2012 while Idea Cellular and Aircel lost 1.56 million users and 1.46 million users to take their base to 114.14 million and 65.32 million respectively.
Uninor lost 4,37,915 subscribers and its user base is now reduced to 40.60 million.
State-run BSNL and MTNL lost 81,021 and 1,813 users and their subscriber base now stands at 99.90 million and 5.30 million respectively.
Reliance Communications, however, added 1,08,990 new users during the period to take its user base to 134.11 million while Loop added 20,805 new subscribers and its base now stands at 3 million users.
Wireline subscriber base declined from 30.95 million at the end of October 2012 to 30.87 million at the end of November 2012, Trai said.
Trai said during November "the share of urban wireless subscribers has decreased from 62.68 per cent to 62.19 per cent whereas share of rural wireless subscribers has increased from 37.32 per cent to 37.81 per cent."
It added the overall wireless teledensity in the country has reached 73.02 at the end of November.
Total broadband subscriber base has increased from 14.81 million at the end of October 2012 to 14.88 million at the end of November 2012, there by showing a monthly growth of 0.47 per cent.