| SICHO TELECOM (HK) LIMITED | Private company limited by shares | Live |
| ONE SIDE TELECOM (HOLDING) LIMITED | Private company limited by shares | Dissolved |
| SIFA TELECOM LIMITED | Private company limited by shares | Live |
| SIGNAL TELECOM CO. LIMITED | Private company limited by shares | Dissolved |
| SIGNAL NETWORK TELECOM LIMITED | Private company limited by shares | Dissolved |
| SIGTO TELECOM (H.K.) LIMITED | Private company limited by shares | Dissolved |
| Silver Fox Telecom Limited | Private company limited by shares | Live |
| Simtoo Telecom China Co. Limited | Private company limited by shares | Live |
| SINCERE TELECOM LIMITED | Private company limited by shares | Live |
| SUN SING TELECOM COMPANY LIMITED | Private company limited by shares | Dissolved |
| TIN SING TELECOM LIMITED | Private company limited by shares | Live |
| SING FAI TELECOM COMPANY LIMITED | Private company limited by shares | Dissolved |
| SING NGAI TELECOM & COMPUTER COMPANY LIMITED | Private company limited by shares | Live |
| Hong Kong Sing Hop Telecom Company Limited | | Live |
| SING LEE (ISDN) TELECOM LIMITED | Private company limited by shares | Dissolved |
| TUNG SING TELECOM COMPANY LIMITED | Private company limited by shares | Dissolved |
| SINKO TELECOM (HK) CO., LIMITED | Private company limited by shares | Dissolved |
| Sino Telecom Co., Limited | Private company limited by shares | Live |
| SINO TELECOM (HK) LIMITED | Private company limited by shares | Live |
| SINO TELECOM INTERNATIONAL (HK) LIMITED | Private company limited by shares | Live |
| TELECOM SINO (HONG KONG) LIMITED | Private company limited by shares | Dissolved |
| SINO TELECOM SERVICES COMPANY LIMITED | Private company limited by shares | Live |
| SINO TECH TELECOM LIMITED | Private company limited by shares | Dissolved |
| SINO-LINK TELECOM LIMITED | Private company limited by shares | Dissolved |
| SINOST TELECOM LIMITED | Private company limited by shares | Dissolved |
| Sinovo Telecom Co., Limited | Private company limited by shares | Live |
| SiteTalk Telecom Limited | Private company limited by shares | Dissolved |
| SKYLINE TELECOM HK LIMITED | Private company limited by shares | Live |
| SKYLINE TELECOM LIMITED | Private company limited by shares | Live |
| SKYLINK TELECOM LIMITED | Private company limited by shares | Dissolved |
| CIXI SKYLINK TELECOM FACTORY LIMITED | Private company limited by shares | Live |
| SkyNet Telecom Limited | Private company limited by shares | Dissolved |
| Skynet Telecom Company Limited | Private company limited by shares | Live |
| SKYONE TELECOM CO. LIMITED | | Live |
| SKYROCK TELECOM NETWORK CO., LIMITED | Private company limited by shares | Live |
| SKYTECH TELECOM LIMITED | Private company limited by shares | Dissolved |
| SKYWARD TELECOM HK LIMITED | Private company limited by shares | Live |
| SKYWAY TELECOM CO., LIMITED | Private company limited by shares | Live |
| HONG KONG SKYWORLD TELECOM CO., LIMITED | Private company limited by shares | Live |
| NEW SMART TELECOM LIMITED | Private company limited by shares | Live |
| SUN SMART TELECOM LIMITED | Private company limited by shares | Live |
| BD SMART TELECOM LIMITED | Private company limited by shares | Live |
| WIN SMART TELECOM LIMITED | Private company limited by shares | Live |
| SMART TELECOM LIMITED | Private company limited by shares | Live |
| Smart Key Telecom Limited | Private company limited by shares | Live |
| Smart Ant Telecom Limited | | Live |
| Smart Care Telecom Limited | | Live |
| SMARTWIN TELECOM LIMITED | Private company limited by shares | Dissolved |
| SMILE TELECOM TECHNOLOGY CO., LIMITED | Private company limited by shares | Dissolved |
| Snsent Telecom Limited | Private company limited by shares | Live |
| S.O.E. TELECOM LIMITED | Private company limited by shares | Dissolved |
| Jaky Software and Telecom Limited | Private company limited by shares | Live |
| SOHO TELECOM LIMITED | Private company limited by shares | Live |
| IMX TELECOM SOLUTIONS LIMITED | Private company limited by shares | Dissolved |
| BPI TELECOM SOLUTIONS LIMITED | Private company limited by shares | Dissolved |
| Acel Telecom Solutions Limited | | Live |
| EastGate Telecom & Solutions Limited | Private company limited by shares | Live |
| SONIC TELECOM LIMITED | Private company limited by shares | Dissolved |
| Sonic Telecom (HK) Limited | Private company limited by shares | Live |
| NEW SONIC INTERNATIONAL TELECOM LIMITED | Private company limited by shares | Live |
| SOOWOO TELECOM LIMITED | Private company limited by shares | Live |
| SOUNDTECH TELECOM LIMITED | Private company limited by shares | Dissolved |
| ONE SOURCE TELECOM HONG KONG LIMITED | Private company limited by shares | Live |
| EXCEL SOURCE TELECOM INFRASTRUCTURE LIMITED | Private company limited by shares | Live Commenced dormancy on 17-Jul-2013 |
| SKY SOURCE TELECOM INSTRUMENT MANUFACTURING LIMITED | Private company limited by shares | Dissolved |
| SOUTH-EAST ASIA TELECOM ("SEAT") COMPANY LIMITED | Private company limited by shares | Dissolved |
| SOUTHEAST TELECOM HOLDING GROUP LIMITED | Private company limited by shares | Live |
| CHINA SOUTHEAST TELECOM (HONG KONG) COMPANY LIMITED | Private company limited by shares | Live |
| SOUTHERN TELECOM LIMITED | Private company limited by shares | Dissolved |
| SOUTHERN TELECOM LIMITED | Private company limited by shares | Live |
| SPACE TELECOM LIMITED | Private company limited by shares | Live |
| NEW SPACE TELECOM LIMITED | Private company limited by shares | Live |
| TELECOM SPARKLE LIMITED | Private company limited by shares | Live |
| SPEAK TELECOM LIMITED | Private company limited by shares | Live |
| TELECOM SPECIALS MOBILE PHONE LIMITED | Private company limited by shares | Dissolved |
| NEW SPEED TELECOM LIMITED | Private company limited by shares | Live |
| SPHERIS TELECOM LIMITED | Private company limited by shares | Live |
| SPIRIT TELECOM LIMITED | Private company limited by shares | Live |
| SPIX TELECOM LIMITED | Private company limited by shares | Live |
| SPORT TELECOM LIMITED | Private company limited by shares | Live |
| SPRINT TELECOM COMPANY LIMITED | Private company limited by shares | Live |
| Sprite Telecom Limited | Private company limited by shares | Live |
| TELECOM SQUARE HK LIMITED | Private company limited by shares | Live |
| TELECOM SQUARE TRADING LIMITED | Private company limited by shares | Dissolved |
| SROT TELECOM LIMITED | Private company limited by shares | Live |
| STAR TELECOM PCN LIMITED | Private company limited by shares | Dissolved |
| STAR TELECOM LIMITED | Private company limited by shares | Live |
| ASIA STAR TELECOM LIMITED | Private company limited by shares | Live |
| FINE STAR TELECOM LIMITED | Private company limited by shares | Dissolved |
| GOLD STAR TELECOM COMPANY LIMITED | Private company limited by shares | Dissolved |
| STAR TELECOM HOLDING LIMITED | Private company limited by shares | Live |
| PACIFIC STAR TELECOM LIMITED | Private company limited by shares | Dissolved |
| STAR TELECOM PROPERTIES LIMITED | Private company limited by shares | Live |
| TRUE STAR TELECOM CO., LIMITED | Private company limited by shares | Live |
| STARISE TELECOM LIMITED | Private company limited by shares | Live |
| STARRY SKY TELECOM LIMITED | | Live |
| STARWAVE TELECOM LIMITED | Private company limited by shares | Live |
| STARWAY TELECOM LIMITED | Private company limited by shares | Live |
| STONEHENGE TELECOM HONG KONG LIMITED | Private company limited by shares | Dissolved |
| TELECOM STORE LIMITED | Private company limited by shares | Dissolved |