If all those nuisance marketing calls on your mobile are driving you mad, help is at hand. SmarTone-Vodafone says it has just the app to get rid of them. The 3G network operator's new service, Call Guard, was launched yesterday and is ready for download from the respective online application stores of Apple iOS, Android and BlackBerry OS. SmarTone-Vodafone chief executive Douglas Li said the service is unique among local 3G mobile carriers and designed to help subscribers regain control over what is a worsening problem of nuisance calls. 'Based on statistics from our network and market research, we estimate that the population of Hong Kong [mobile phone users] receives over two million marketing calls a day, with the overwhelming majority of these calls being uninvited,' Li said. 'Call Guard enables our customers to collaborate together in identifying and collectively barring these nuisance calls.' Once users have downloaded the app and registered for the service, they simply input the nuisance callers' numbers and these will be blocked for all Call Guard subscribers. Users can also individually create a trusted callers list. A function called 'block last caller' allows a user to add a nuisance call that does not reveal its caller ID to the barred numbers list. The app's 'my trusted callers only' function is especially geared for users travelling abroad who want to avoid paying expensive roaming charges from nuisance calls. Li said nuisance marketing calls have thrived in Hong Kong because of low telephone costs in the city compared with other markets. In June, Privacy Commissioner Allan Chiang Yam-wang disclosed that Citibank, Fubon Bank, Industrial and Commercial Bank of China (Asia) and Wing Hang Bank sold the personal data of tens of thousands of customers to insurance or marketing companies without their consent. The data sold included clients' names, addresses, phone numbers, sex and birthdays. The privacy commissioner's report did not say how much the banks made or how many customers were affected. Chiang expressed disappointment that banks had not learned from the lessons of the Octopus Card privacy-for-sale scandal last year. Smart card payments system operator Octopus sold the personal information of millions of its clients to business partners. It denied this at first, but later admitted making HK$44 million from that transaction. Call Guard is available at HK$15 a month in a 12-month contract and HK$20 for a 20-month subscription.