Zhang Lei, a veteran entrepreneur based in Beijing, has a burning ambition: to grow his startup YeeCall to be even more spectacular than WeChat, Tencent Holdings Ltd's instant messaging app that metamorphosed into an all-in-one killer e-tool for its more than 800 million users worldwide.

For a start, he is betting big on instant messaging. But instead of competing directly with the Chinese internet giant, he is taking a detour. His sights are set on India.

Launched in 2015, YeeCall, an app that offers high-quality and free internet-based voice calls, claims it had more than 10 million users by the end of June, half of them in India.

Right from the word go, YeeCall targeted overseas markets. "Any company involved in the internet business would want to choose a market with a huge potential for growing user numbers and a strong momentum in business. India is the place to be in," Zhang, co-founder and chief executive officer of YeeCall, said.

Industry insiders agree. Wang Yao, vice president in charge of product development at the Shenzhen-based Leomaster, said India holds more advantage than China in product development and distribution because there are no internet heavyweights that control distribution channels in India.

Leomaster, which develops app lock for Android systems to protect users' privacy, has a 10-strong team in India.

India's strong economic growth and rising number of smartphone users are key factors, Zhang said. Other factors that persuaded Zhang to start up in India were a crowded market and fierce competition in China.

Although the niche of internet-based voice calls and instant messaging is no longer fancied by investors and entrepreneurs, Zhang believes it remains the gateway to connect users of mobile internet.

"The fact that it's not chased by many entrepreneurs should mean there are fewer newcomers, which, in turn, would mean less competition for funding in this segment. This gives us adequate time to produce the next big thing in this space."

YeeCall started its overseas trials in October 2015 and is said to have attracted a rising number of users in India, where WhatsApp leads the pack, followed by Hike, Facebook Messenger, Google Hangout/GTalk and Telegram.

Several others－Viber, Skype, WeChat, Line, BlackBerry Messenger, SnapChat and Instagram－trail them. In India, national and international phone calls remain expensive, so industry experts feel technology that could make such calls legal and inexpensive could prove a breakthrough.

Undeterred by market leader WhatsApp and a large number of existing players in the market, Zhang's 30-member YeeCall team has been gearing up to offer more features, including social networking.

Being a startup, YeeCall has the advantage of quick decision-making, that could help meet the market needs, Zhang said. "WhatsApp doesn't offer video chat and group video chat, but we do."

Zhang and his team work 14 hours a day, seven days a week. Within two weeks in October, they upgraded the app three times.