Bharti Airtel Limited , commonly known as Airtel, is an Indian telecommunications company that operates in 20 countries across South Asia, Africa and the Channel Islands. It operates a GSM network in all countries, providing 2G or 3G services depending upon the country of operation. Airtel is the fifth largest telecom operator in the world with about 230.8 million subscribers across 19 countries at the end of June 2011. It is the largest cellular service provider in India, with over 171.85 million subscribers as of August 2011. Airtel is the 3rd largest in-country mobile operator by subscriber base, behind China Mobile and China Unicom.