Airtel

Bharti Airtel Limited, commonly known as Airtel, is an Indian multinational telecommunications services company headquartered at New Delhi, India. It operates in 20 countries across South Asia, Africa and the Channel Islands. Airtel has GSM network in all countries in which it operates, providing 2G, 3G and 4G services depending upon the country of operation. Airtel is the world's third largest mobile telecommunications company with over 261 million subscribers across 150 countries as of August 2012.[4] It is the largest cellular service provider in India, with 183.61 million subscribers as of November 2012.[5] Airtel is the third largest in-country mobile operator by subscriber base, behind China Mobile and China Unicom.
Airtel is the largest provider of mobile telephony and second largest provider of fixed telephony in India, and is also a provider of broadband and subscription television services. It offers its telecom services under the airtel brand, and is headed by Sunil Bharti Mittal. Bharti Airtel is the first Indian telecom service provider to achieve Cisco Gold Certification.[6] It also acts as a carrier for national and international long distance communication services. The company has a submarine cable landing station at Chennai, which connects the submarine cable connecting Chennai and Singapore.
Airtel is credited with pioneering the business strategy of outsourcing all of its business operations except marketing, sales and finance and building the 'minutes factory' model of low cost and high volumes. The strategy has since been copied by several operators.[7] Its network—base stations, microwave links, etc.—is maintained by Ericsson and Nokia Siemens Network[8] whereas business support is provided by IBM,[9] and transmission towers are maintained by another company (Bharti Infratel Ltd. in India).[10] Ericsson agreed for the first time to be paid by the minute for installation and maintenance of their equipment rather than being paid up front,