CSL Mobile Limited () is a Hong Kong telecommunications company, which operates mobile network brands of "csl", "1O1O" and "Club SIM". CSL is a subsidiary of Hong Kong Telecom (HKT) and was Hong Kong's first mobile communications operator established in 1983, and also the first network to launch the world’s first dual band 4G LTE network with DC-HSPA+. The brand CSL was under different legal person in its operating history, namely Communication Services Limited, which known as Hong Kong Telecom CSL Limited from 1990 to 1999, and then Cable & Wireless HKT CSL Limited from 1999 to 2001, and then Hong Kong CSL Limited from 2001 (it became a subsidiary of CSL Limited after the formation of CSL New World Mobility), CSL Limited (formerly known as New World PCS) and CSL Mobile Limited; The current legal person of the brand, CSL Mobile Limited, was formally known as PCCW Mobile HK Limited. It was the result of the merger of the brands CSL and PCCW Mobile. History In the 1990s, CSL was a company of PCCW (formerly HKT). In 2002, PCCW sold CSL. In 2005, PCCW re-entered the mobile network operator business by acquiring SUNDAY and setting up a new brand "PCCW Mobile". In 2014, HKT (a member of PCCW Group) acquired CSL New World Mobility and its subsidiaries such as CSL Limited and New World Mobility. In 2014, the legal person of PCCW Mobile was renamed into CSL Mobile Limited. However, it used the brand CSL instead. CSL was an abbreviation for Communication Services Limited and their original branding of "Create a Simple Life". The CSL brand, logo and corporate colour (green) were all updated in August 2011 and again in recent year. Timeline 1980: Communication Services Limited was incorporated. 1984: CSL, a wholly owned subsidiary of Hong Kong Telecom, launches Hong Kong's first public mobile radiotelephone service using NEC's Advance Mobile Telephone System. July 1993: CSL launches its GSM service. June 1997: CSL launches its GSM 1800 network. December 1997: CSL acquires Pacific Link Communications. The acquisition included the digital cellular phone services (D-Amps), PCS (GSM1800) and radio paging services. 2000: PCCW Limited buys HKT, including subsidiary CSL (known as Hong Kong Telecom CSL Limited at that time), for an estimated US$38 billion from Cable & Wireless. February 2001: PCCW sells 60% of CSL to Telstra for $3.05 billion, in a joint venture called "Regional Wireless Company" (RWC). July