SINGAPORE - A local start-up funded by investors including Creative Technology co-founder Sim Wong Hoo has debuted a mobile app that provides free Internet calls to landlines and mobile phones.

All calls made using the app, called Nanu, will be free - including calls to non-Nanu users.

The app, which was launched on Tuesday for Android phones, was developed by Gentay Communications.

The company did not disclose the amount Mr Sim and other investors invested in the company.

Co-founder and chief executive officer Martin Nygate told The Straits Times: "It is sufficient for us to further develop the product for quite a while without having to raise additional funds."

To provide the free calls, users will have to listen to a short advertisement that will play over the ringtone while the call is waiting to be picked up.

"The revenue from the advertisement will subsidise the cost of the call so that consumers can make all calls completely free."

Nanu can be used on 2G, 3G, 4G or where there is Wifi.

The difference between Nanu and other Internet phone services like Skype and Viber is that it uses ultra low-bandwidth technology that allows it to provide quality Internet calls, the company said.