CSL Mobile Limited (Chinese: 香港移動通訊有限公司; Cantonese Yale: Hēunggóng yìhduhng tūngseun yáuhhaahngūngsī) 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,[1] and also the first network to launch the world’s first dual band 4G LTE network with DC-HSPA+.

[2] It was the result of the merger of the brands CSL and PCCW Mobile.

CSL was an abbreviation for Communication Services Limited[6][7] and their original branding of "Create a Simple Life".

[8] The CSL brand, logo and corporate colour (green) were all updated in August 2011 [9] and again in recent year.