Within Hong Kong, you may set different kinds of call forwarding commands to forward calls to your fixed-line numbers and/or voicemail. If these commands are not deactivated when you are travelling overseas (roaming), one incoming call charge plus one outgoing call charge may be incurred due to one single missed call because your call is “received” (incoming) by the roaming service provider before an outgoing call is routed back to a Hong Kong number.

For the sake of convenience, you may store overseas numbers in your mobile phone book with the IDD prefixes that you use frequently. However, mobile phones may recognize only the few last digits of each phone number. Phone number “111185298866622” is stored as “Mary”, but a missed call from “Mary” is actually “+85298866622” where “+” is the default IDD prefix of your mobile service provider. The same will happen if you reply to an incoming overseas call directly.

There are many content services such as premium voice, ring tone/graphic downloads and/or internet/WAP access which are not provided by mobile operators. Their charging mechanisms, service terms and conditions are not the same. You should first study the pricing mechanisms, terms and conditions of the services to avoid possible expensive charges or usage dispute afterwards.

Some mobile phones are so “user-friendly” that you may make an outgoing call by just pressing one key (e.g. pressing the “send” key will make the last call), or send an SMS by just pressing one single key a few times. To avoid making calls or sending SMS unintentionally, your keypad should always be locked when it is not in use.