The total number of GSM subscribers in the country crossed 677.85 million as against 670.57 million in April.
Airtel currently has 185 million subscribers.
Idea Cellular followed Airtel by adding 1.8 million subscribers for a total of 116 million subscribers.
Uninor, which stands to lose all its 22 licences cancelled following the Supreme Court's ruling earlier this year, added 1.5 million subscribers to take its subscriber count to 45 million.
Vodafone added 1.2 million users, taking its subscribers base to 152 million. Aircel added 0.8 million subscribers for a total of 64 million users.
CDMA player Sistema Shyam TeleServices (SSTL), in a separate statement, said it added 2,54,995 customers in May to have a total customer base of 16.3 million. The firm which operates in India under MTS brand also stands to lose its licences following the apex court's order.
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