Various call-filtering apps are available for download by smartphone users for screening telemarketing calls. These apps generally collect telemarketers’ numbers through voluntary reports from members of the public for establishing a database of such numbers. When a call is made to a user, the apps will assist the user to identify whether the call is a telemarketing call by checking the calling number against the database.

Before installing and using call-filtering apps, smartphone users should take note of the following:

• The call-filtering apps rely on the database of telemarketers’ numbers compiled based on the voluntary reports by the public. There is no guarantee that the database is accurate or complete.
• Install only apps from official application stores or trusted sources.
• Read carefully the terms and conditions, including whether the apps are provided free of charge or at a fee.
• Assess whether the apps really meet your needs and if possible, consult your friends and relatives who have used the apps.
• Scrutinise thoroughly all permission requests of the apps, in particular whether the apps seek to obtain information irrelevant to provision of call-filtering service.
• Some operators also provide call-filtering services. Users may obtain details from them.