"Mobile bill shock" refers to the situation when mobile users receive mobile bills with unexpectedly high charges. It is mostly caused by inadvertent or unintended use of mobile data services or roaming services:

Unintended use of mobile data services

Unintended use of roaming services

Unintended use of mobile data services

Even if you have subscribed to a “voice only” mobile service plan, your mobile device may still be able to access the Internet via mobile network and therefore consumes mobile data. This will incur mobile data service charges, which are not included in your monthly service fee and are usually charged based on the amount of mobile data you have used. You may refer to "Understanding Mobile Data" for more information about when mobile data will be consumed. You should check with your mobile operator whether usage of mobile data service is allowed under your “voice only” mobile service plan, and if yes, the corresponding service charges. If you do not need mobile data services, you may check with your mobile operator whether such function could be deactivated. Alternatively, you may deactivate the mobile data function of your mobile device.

Sometimes, you may use mobile data services unintentionally. This may happen when you think that your mobile device is connected to Wi-Fi network, but in fact the Wi-Fi signal is too weak and your mobile device switches to connect to mobile network instead.

To avoid unintended use of mobile data services, you may:

• switch off the mobile data function of your mobile device when such service is not required;
• switch off Wi-Fi assist function (which will switch your device to a mobile network when the Wi-Fi signal is weak) of your mobile device when such service is not required;
• check your mobile device regularly to ensure that it remains connected to Wi-Fi network when you intend to use Wi-Fi service; and
• keep track of your mobile data usage regularly.

Unintended use of roaming services

Roaming services are generally more expensive than local mobile services. Unintended use of roaming services may incur unexpectedly high charges. Consumers are advised to take note of the following general guides in order to avoid unintended use of mobile roaming services:

• Avoid Unintended Use of Mobile Roaming in Boundary Areas
• Be Mindful of Unexpected Mobile Data Service Charges While Roaming Overseas
• Other Mobile Data Services Options While Travelling Abroad

 

Measures Implemented by Mobile Operators to Prevent Mobile Bill Shock

The Office of the Communications Authority (OFCA) notes that many mobile operators have implemented various voluntary measures to prevent mobile bill shock, including:

• allowing customers to opt-out individual services;
• setting a charge ceiling;
• setting a usage cap for usage-based mobile services; and
• alerting customers through short messages when their pre-determined usage threshold is reached.

The measures adopted by individual mobile operators are published on OFCA's website . While the information will be updated periodically and upon advice by mobile operators on new or enhanced initiatives they have taken on board, consumers should note that mobile operators may adjust their service packages and mobile bill shock measures from time to time, and they are strongly advised to consult individual mobile operators directly on their latest initiatives, service terms and conditions, as well as charging schemes and methods and other pertinent details prior to committing themselves to any mobile data services.