GSM subscriber base in India reached 677.85 million during last month, according to data released by industry body COAI. According to latest figures released on Thursday telecom operators added 7.27 million subscribers last month, taking the total user base to 677.85 million.

Bharti Airtel maintained its lead by adding maximum number of subscribers in May, according to data released by industry body COAI. Airtel added 2.01 million users in May taking its total subscriber base to 185.30 million, Uninor, added 1.52 million new customers in May, taking its user base to 45.08 million.

The company, along with other operators such as Videocon, Etisalat DB, STel and Sistema Shyam Teleservices (SSTL), are facing the threat of closure after the verdict.

Their licences are valid up to September 7, following which they will have to participate in the auction to buy spectrum to continue operations.

Country's third largest operator Vodafone India added 1.20 million customers in May, taking its subscriber base to 152.49 million. The operator has a market share of 22.50% as on May 31, 2012.

Aditya Birla group firm Idea Cellular added 1.76 million new subscribers during the month, while Videocon and Aircel added 0.13 million and 0.80 million new users, respectively. State owned telecom firms BSNL and MTNL, however, did not fare well this month.

While BSNL added just 1,735 new users, MTNL, which operates in Delhi and Mumbai, lost 0.17 million customers during the month. The subscriber base of BSNL and MTNL stood at 94.68 million and 5.32 million, respectively.

The COAI data excludes the subscriber numbers from Reliance Communications. SSTL operates under MTS brand and whose licence was also cancelled reports its numbers to CDMA body AUSPI.

SSTL said it has added 0.25 million customers in May taking its total customer base to 16.31 million.