Like most of the world, Hong Kong uses the GSM cellular phone system. Mobile phones are part of everyday life, and there are plenty of providers and tariffs to choose from.
If you intend to stay in Hong Kong for a while and don’t want to waste hundreds of dollars on roaming fees, you should get a Hong Kong mobile number, either through a prepaid card or a fixed tariff.
Note that in Hong Kong some mobile operators will charge you for incoming calls as well (similar to the US). However, these charges are still a lot lower than international roaming fees for incoming calls.
Prepaid SIM cards are available everywhere. Cards are normally with a certain number of minutes and cost around HK$ 200. Most companies charge per minute, so if you make a call of 1 minute and 1 second, you will be charged for two minutes. Be aware that cards are normally only valid for 180 days after the last recharge. After this period the card expires with no refund available and you lose the number.
If you want to use your mobile phone from home in Hong Kong, you must check whether it supports the GSM network first. If it does, you then need to check whether the phone is locked to your old mobile provider, if it is you will need to get it unlocked (many telecommunications stores can do this for you).
Before you buy a SIM card or opt for a mobile plan, shop around for available tariffs. When choosing a tariff, make sure you are aware of you individual calling habits (where/how often do you call?). Main mobile operators in Hong Kong are: