Students are advised to get a Hong Kong mobile number.
You can visit convenience stores, supermarkets, and stores of mobile network operators to purchase a SIM card for your mobile phone or subscribe to a monthly mobile service plan in person at the branches of service providers once you are settled.
If you purchase SIM card issued by telecommunications service providers in Hong Kong, you have to complete real-name registration with your own original identity document so as to activate the card. The registration is easy and fast, you can refer to the general registration steps section and the weblinks by telecommunications service providers.
Also check out free Wi-Fi services across the city here.