Indian GSM telecom operators added 11.10 million subscribers in April, taking the all-India GSM cellular subscriber base to 580.66 million, cellular operators' association COAI today said.

The GSM subscriber base stood at 569.55 million at the end of March, 2011, with an addition of 14.49 million.

Bharti Airtel, the largest GSM player, added 2.41 million users in April, taking its total subscriber base to 164.61 million, data released by the Cellular Operators Association of India (COAI) showed.

It had 28.35 per cent market share as of the end of April 2011, it added.

This is the lowest subscriber addition since October, 2009, when 10.76 million users were added to the GSM network

Rival Vodafone Essar, with a 23.59 per cent market share, notched up 2.40 million new subscribers during the month. Its subscriber base stood at 136.97 million at the end of the reported month.

Aditya Birla group firm Idea Cellular added 2.45 million users during the month to take its total user base to 91.95 million, while Aircel added 1.10 million customers to take its subscriber base to 55.95 million.

State-run telecom firms BSNL and MTNL added 689,361 and 14,633 new users, respectively, taking their subscriber base to 87.14 million and 5.21 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 which Indian telcos offer services on 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.