Airtel said in a statement said that it "has crossed the 200 million mobile subscriber mark in India, further consolidating its leadership position in the world's second-largest mobile market."
The company is in its 20th year of telecom services. Airtel got its first permits for mobile telephony in November 1994 and started services in 1995.
Airtel is the largest telecom operator in India, in terms of both customers and revenue. It is the fourth-largest mobile operator in the world by subscribers.
The latest 100 million users were added in less than five years, according to the Airtel statement. It had crossed the 100 million mark in 2009.
The company led the mobile market with a 28.1 percent share at the end of January, according to data released by the Cellular Operators Association of India.
Vodafone was in second place with 162.1 million users and a 23.06 percent market share, COAI said.
Airtel on Tuesday announced it was buying Loop Mobile, a Mumbai-based telecom operator with roughly 3 million subscribers. Once the deal goes through, Airtel will have over 7 million subscribers in Mumbai, helping it edge ahead of Vodafone's 6.9 subscribers (November 2013 numbers).
The company did not disclose the size of Loop Mobile deal but sources close to the agreement said it is for about Rs. 700 crores. Loop Mobile has a debt of Rs. 400 crores, which is likely to be included in the final transaction.Under the proposed transaction, Loop Mobile's 2G-enabled network supported by 2,500 plus cell sites will also become part of Airtel's network which has over 4,000 cell sites at present.