GSM telecom operators added 9.53 million subscribers in May, taking the all-India GSM cellular subscriber base to 590.19 million.
According to the Cellular Operators Association of India (COAI), the GSM subscriber base stood at 580.66 million at the end of April 2011, with the addition of 9.53 million new users.
This is the lowest level of subscriber addition since October 2009, when 10.76 million users were added to the GSM network.
Bharti Airtel, the largest GSM player, added 2.45 million users in May, taking its total subscriber base to 167.06 million, the COAI data showed.
The company had a 28.31 per cent market share as at the end of May 2011, it added.
Vodafone Essar, with a 23.62 per cent market share, notched up 2.44 million new subscribers and its subscriber base stood at 139.42 million.
Aditya Birla group firm Idea Cellular added 1.8 million users during the month to take its total user base to 93.75 million, while Aircel added 1.11 million customers to take its subscriber base to 57.06 million.
State-run telecom firms BSNL and MTNL added 0.47 million and 20,604 new users, respectively, taking their subscriber base to 87.61 million and 5.23 million, respectively.
The COAI data excludes Reliance Communications.
GSM (Global System for Mobile Communications) is the most popular standard for mobile telephony systems in the world.
The other technology platform on which Indian telcos offer services is CDMA, where players such as Tata Teleservices (TTSL), Reliance Communications and MTS are the main operators.
TTSL and Reliance Communications offer both GSM and CDMA services.