Telkomsel is the leading operator of cellular telecommunications services in Indonesia by market share.

By the end of September 2008, Telkomsel had 60.5 million customers which based on industry statistics represented an estimated market share of approximately 46%.

Telkomsel provides cellular services in Indonesia, through its own nationwide dual-band GSM 900-1800 MHz, 3G network, and internationally, through 323 international roaming partners in 170 countries (end of September 2008). In September 2006, Telkomsel became the first operator in Indonesia to launch 3G services.      

The company provides its subscribers with the choice between two prepaid cards-simPATI and Kartu As, or the post-paid kartuHALO service, as well as a variety of value-added services and programs.

Telkomsel's operations in Indonesia have grown substantially since the commercial launch of its post-paid services on 26 May 1995. In November 1997, Telkomsel became the first cellular telecommunications operator in Asia to introduce rechargeable GSM pre-paid services.

Telkomsel's gross revenues have grown from Rp 3.59 trillion in 2000 to Rp 44.38 trillion in 2007. Over the same period, the total number of Telkomsel's cellular subscribers increased from approximately 1.7 million as at 31 December 2000 to 47.9 million as at 31 December 2007.

Telkomsel has the largest network coverage of any of the cellular operators in Indonesia, providing network coverage to approximately 95% of Indonesia's population and is the only operator in Indonesia that covers all of the country's provinces and regencies, and all counties ("kecamatan") in Sumatra, Java, and Bali/Nusra. The company offers GSM Dual Band (900 & 1800), GPRS, Wi-Fi, EDGE, and 3G Technology.