A Singapore startup is looking to shake up the telecommunications industry with a pledge to provide free overseas calls and "eliminate phone bills".

Gentay Communications on Tuesday launched its mobile VoIP app, called Nanu, touted to use "ultra-low bandwidth technology" that allows the company to offer quality calls even on 2G networks.

The startup developed a a proprietary technology that uses "vastly less bandwidth" than conventional VoIP communications such as Skype, Line, and Viber, said Martin Nygate, founder and CEO of Gentay, in a phone interview with ZDNet. In comparison to Skype, for instance, Nanu consumes 80 percent less bandwidth.

He added that apps such as Skype and Line work on P2P (peer-to-peer) networks, and this means the call can go through several POPs before reaching the recipient. This results in call degradation and latency, he said, noting that Nanu runs on a different architecture that can route calls either through a P2P network or dedicated lines, which the company leased from various telcos worldwide.

Asked to elaborate on how the Gentay technology works, Nygate refused to provide details, saying only that it's fundamentally a VoIP technology and was originally developed to support ship-to-shore voice communications for the maritime industry, which typically run on low bandwidth over satellite.

It is this unwillingness to divulge the details, of what he describes as the company's "secret sauce", that has led to his decision not to patent the technology, which would mean having to document and publish it.

Free calls for Nanu-to-Nanu, limited free calls for non-Nanu

To fuel downloads for the app, Gentay is offering unlimited free calls if both parties are Nanu users. For calls made from a Nanu to a non-Nanu user, including landline phones, the first 15 minutes will be free for the first 1 million users. The free minutes can be used to call landlines in 73 countries including Australia, China, India, Malaysia, South Korea, Singapore, Thailand, the United States, and United Kingdom.

The app is currently available only for Android devices, though support for Apple iOS will be launched in November and Windows Mobile to follow shortly after, Nygate said, adding that support for feature phones can be added as well if there is demand--specifically, advertiser demand, because that's how the startup will get its revenue.

Gentay collects revenue from playing voiceover advertisements over the ringtone while the caller is waiting for the receiving end to pick up. A banner ad will also be displayed on the screen when the caller is ready to end the call, which will redirect to the advertiser's URL if selected.

"The problem with banner ads is that they're too small and have minimum impact. So we've complemented that with a non-intrusive ad over the ringtone while the caller waits for his call to be answered," Nygate noted, adding that the voiceover ad will run for as long as the call remains unanswered. The average time before a call is connected and picked up is 7 seconds, he said.

Companies including Nestle, KFC, Garuda, HTC, and Bank of Philippine Islands have already signed on as advertisers, he added. And the startup will need advertising revenue to continue offering free overseas calls.

Nygate said: "Our mission is to eliminate the cost of phone calls, so our target market is anyone who doesn't want to pay hefty phone bills anymore. We want to give free unlimited calls to everyone, everywhere...as we grow and start generating ad revenue, our mission is to expand that to free calls everywhere."

Asked what would be the breaking point to enable that, he couldn't say, but did reveal some numbers the company was targeting. "Once we reach 1 million subscribers, only then can we start generating ad revenue. We expect to reach that number by end-September, and to hit 15 million by end-December," he said, adding that the company expects to touch 150 million Nanu subscribers by December 2015.

He explained that giving unlimited free calls will be a gradual process, for example, increasing from the initial free 15 minutes to 50 minutes when a certain ad revenue is achieved. "I project by the early part of next year, we can vastly increase free calls," he said. "The advertising revenue will grow and eventually allow us to offer unlimited free calls. What this actually means is the end of phone bills as we know them."

Gentay currently has 10 employees, including Nygate's son Daniel who is the company's CTO, but this number will double in the next couple of months, the CEO said.