Bharti Airtel Limited, commonly known as  Airtel, is an Indian multinational telecommunications services company based in New Delhi. It operates in 18 countries across South Asia and Africa, as well as the Channel Islands. Currently, Airtel provides 4G and 4G+ services all over India and 5G service in selected cities. Currently offered services include fixed-line broadband, and voice services depending upon the country of operation. Airtel had also rolled out its VoLTE technology across all Indian telecom circles.  It is the second largest mobile network operator in India and the second largest mobile network operator in the world. Airtel was named India's 2nd most valuable brand in the first ever Brandz ranking by Millward Brown and WPP plc 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 adopted by several operators.  Airtel's equipment is provided and maintained by Ericsson, Huawei, and Nokia Networks[9] whereas IT support is provided by Amdocs. The transmission towers are maintained by subsidiaries and joint venture companies of Bharti including Bharti Infratel and Indus Towers in India. Ericsson agreed for the first time to be paid by the minute for installation and maintenance of their equipment rather than being paid upfront, which allowed Airtel to provide low call rates of ₹1 (1.3¢ US)/minute.