SK Telecom was established in March 1984 under the name Korea Mobile Telecommunications Services Corp. (KMTSC; ), but was renamed Korea Mobile Telecommunications Corp. (KMTC; ) in May 1988. It was a subsidiary of the state monopoly phone company, Korea Telecom (now known as
KT Corp.) until KT sold it off in 1994. In June 1994
SK Group (Formerly Sunkyong Group) became Korea Mobile Telecommunications Corporation's largest shareholder. KMTC officially joined the SK Group in January 1997 and changed its name to SK Telecom in March of that year. In October 2000, SK Telecom became the second operator in the world after
NTT DoCoMo to launch a commercial
3G service using
W-CDMA technology. In January 2002, this was followed up by launching the world's first
CDMA2000 1xEV-DO network, offering greatly increased data transmission speeds to preexisting
2G networks. In May 2005, SK Telecom divested 60 percent of
SK Teletech stock to cellphone maker
Pantech. SK remains the second largest shareholder by holding on to the rest of Teletech's stock. In 2006, the well-known "SKY" brand of mobile devices became fully owned by Pantech as it finalized its takeover of SK Teletech.
1984–1993: early years Founded on March 29, 1984, as Korea Mobile Telecommunications Services Corp., the
state-owned carrier introduced
pagers and
car phones to the Korean market. May 1984 saw the launch of the car phone service. Korea Mobile changed its name to Korea Mobile Telecommunications Corp. (KMTC) in May 1988. In July,
AMPS cellular network was initially launched in Seoul metropolitan area. By 1991 nationwide coverage was complete. In April 1993, the South Korean government, through KMTC, adopted CDMA as the national cellular telephone system.
1994–1996: privatization and the CDMA standard Through
privatization, SK Group became Korea Mobile Telecommunications Corp.'s largest shareholder in June 1994.In October 1994, Korea's first CDMA system was introduced to the public for the first time. In January 1995, KMTC reached the one million subscriber mark. Korea Mobile Telecommunications became the third Korean firm to be listed on the
NYSE exchange (
ADR) in June 1996. Later that year South Korea got its first commercial CDMA (IS-95A) network. Operating in Seoul in October, it is considered one of the world's earliest commercial CDMA networks.
1997–2000: international expansion SK Group completed its takeover of KMTC in January 1997, as it became the world's sixth carrier to attain ten million subscriptions. Around that time, it also began constructing the Northeast Asian CDMA belt encompassing China, Japan, Vietnam, and the rest of the Asian continent. In March 1997, to reflect new changes, KMTC changed its name to SK Telecom, and in October, NetsGo, an online service, was launched. In June 1998, SK Telink, the international call service division, started offering commercial overseas call service. In December 1998,
SK Teletech launched its first handset. In April 1999, SK Telecom entered the Mongolian market by co-founding
Skytel LLC with nearly 30 percent ownership stake.TTL, a
wireless plan targeting younger users, and nTOP, a
cellular internet service were launched in July and October 1999, respectively.In December 1999, SK Telecom surpassed ten million subscriber mark, the following month, it launched the world's first commercial
CDMA2000 service. By the end of the year the carrier won a contract for asynchronous
IMT-2000 (WCDMA) facility.
2001–2007: cellular internet and market accrual The new millennium ushered in an era of cross-platform online networks that saw efforts to integrate mobile services, as SK Telecom was exploring new value-creating models such as m-Commerce and satellite DMB Service. In January 2002, an acquisition of Shinsegi Telecomm Inc. was completed. In the same month also, the company deployed world's first commercial synchronous
IMT-2000 facility.In March 2002, the carrier struck international roaming deals between countries using
CDMA and
GSM networks. An agreement was signed with Israel's
Pele-Phone in April to sell proprietary software that will operate on the carrier's existing CDMA network and future 1x-CDMA network. In July, a
MoU was signed with
China Unicom to establish a joint venture. In November two mobile applications 'June' and 'Moneta' were launched. In July 2003, S-Fone, a commercial CDMA network became operative in Vietnam. In August 2003, June became the world's first 3G service to have one million subscribers. In February 2004, SK won a contract for a
joint venture with China Unicom, called UNISK. In March 2004, Hanbyul, the world's first DMB satellite, was launched.
MelOn, an online music store was launched in November 2004. '1mm' and 'Loview,' a digital photo frame service were launched in April and November 2005, respectively. By December, MelOn had four million subscribers.SK Telecom started 2006 with record revenues of . In May the world's first commercial
HSDPA handset was released. May also saw the carrier's entry into the U.S. wireless communication market with
Helio. In June, SK Telecom signed a strategic partnership with
China Unicom to purchase
CB worth $1 billion in its subsidiary, China Unicom Hong Kong. In the same month SK deployed its
WiBro internet network. In April 2007, a project to create
TD-SCDMA, China's
3G wireless broadband equivalent was signed with the Chinese government. Around that time,
S-Fone had two million subscribers in Vietnam.
2008–present: landline and new technologies In November 2008, SK signed an agreement to buy a controlling stake of fixed-line phone company Hanaro Telecom for from a consortium led by
AIG and
Newbridge Capital. The new entity will be the second-largest telecom firm in terms of total assets and revenues next to
KT Corp. In 2013 SK Telecom was the world's first operator to offer a commercial
LTE-Advanced network under the brand name
bandLTE. This coincided with the release of the
Samsung Galaxy S4 LTE-A model, which offered a step-up CPU (
Snapdragon 800 vs.
Snapdragon 600 used in the regular model) and also LTE-Advanced capabilities. SK Telecom supported this handset at launch. On July 6, 2013, it was reported that Apple was in talks with SK Telecom to release the iPhone 5s model on SK's LTE Advanced network. On December 17, 2018, SK Telecom introduced the 'baro' roaming plan which offers unlimited use of international roaming voice calls. As of June 2019, 'baro' has drawn 2.2 million customers and 38 million total calls (with a total of 800,000 hours of voice calls). It also won the 'Best Mobile Technology Breakthrough in Asia' award at the 2019 Asia Mobile Awards carried as section of
MWC19 Shanghai. In October 2020, SK Telecom formed a partnership with Uber Technologies, with a plan to break off mobility operation into a subsidiary called T Map Mobility. In November 2021, SK Telecom spun off of a new company focusing on investments, semiconductors and
ICT, SK Square.
Cybersecurity breach of 2021-2025 On April 18, 2025, SK Telecom informed authorities of a data leak, with full scope of the leak being unknown at the time. The information leaked in this incident includes the USIM authentication key (KI), International Mobile Subscriber Identity (IMSI), device identifier (IMEI), and phone numbers. In response to the breach, SK announced that all of its 23 million subscribers would be eligible for a free USIM card replacement starting from April 28, a week after the company publicly acknowledged the hack. Those who replaced their USIM earlier would be eligible for a refund. However, SK Telecom currently has only 1 million USIM cards available, leading to shortages and customer frustrations. Acting President Han Duck-soo directed related agencies to investigate SK Telecom's hacking countermeasures. SK said they are developing a way to format USIM cards without physically replacing them. In July 2025, Korean Ministry of Science and ICT released a final report of the investigation. Based on the report, SK Telecom was compromised back in 2021 with attackers remaining active in SKT network undetected until 2025. According to the report, SK Telecom failed to properly manage sensitive accounts, encrypt sensitive data and did not respond adequately to previous security breaches (according to the report, SK Telecom detected unauthorized reboot of one of the servers, detected malware but did not inform the authorities), did not store critical security log information for sufficient time. On August 28, 2025, the
Personal Information Protection Commission issued a 134.8 billion won (US$96.9 million) fine on SK Telecom over the data breach. ==Corporate governance==