Reliance Jio Infocomm had also joined the body but the company is yet to start telecom services.
Country's third largest mobile operator Idea Cellular added the maximum number of users at 2.58 million during the month. The user base of Idea Cellular stood at 150.5 million at the end of December.
Idea in a statement said it recorded the highest growth in net additions in the industry, with over 21 million subscribers joining the network in the calendar year 2014.
"Idea's unprecedented growth in the last five years has catapulted it to being the 6th largest operator globally (source: GSMA Intelligence Report for single country operations), from being the 6th largest in India, in subscriber terms," the statement said.
Bharti Airtel added 1.76 million subscribers during December to take its user base to 217.2 million whereas Vodafone added 1.49 million users and its overall base stood at 178.6 million at the end of the month.
Uninor added 12 lakh new users to its network to take its base to 43.6 million during the reported period whereas Aircel added 0.9 million subscribers and its base at the end of December stood at 78.6 million.Videocon added 0.21 million subscribers and state-run MTNL added 22,469 users to its network. The user base of the operators stood at 6.45 million and 3.361 million respectively at the end of December.