Offering free talk time by tapping onto a Wi-Fi or mobile data network, smartphone voice chat apps such as Line, Viber and Tango are giving telcos a run for their money.
These voice over Internet protocol (VoIP) apps act like your normal dialler, integrate into your device's phone book and call history, and some even display a caller's number.
However, both parties must use the same app. Otherwise, calls or messages will not get through and neither will missed calls or messages.
Using KakaoTalk on his iPhone 4, Mr Barry Teo, 34, saves money on overseas and local calls, especially when he is running low on free talk time offered by his monthly plan.
His wife introduced the app, which is immensely popular in South Korea, to him. Still, the trouble is in finding out which of his friends are on the platform.
"My friends are using different apps and it is hard to connect to them," admitted the Shanghai-based sourcing manager.
Free calls on VoIP have been around for many years, with services such as Skype popularising it on computers, even though call quality can falter with poor Internet speeds.
These services have since jumped over to smartphones, where they have multiplied to more than 10 and which allow users to make VoIP calls at any time and place, using their bundled data network.
"With the introduction of data-enabled mobile phones, VoIP has become popular again through mobile apps," said Mr Johan Buse, SingTel's vice-president of marketing.
Call quality not assured
While telcos can benefit from more data use, there is also a cause for concern as a reliance on free calls can eat into its talk-time revenue.
Said MrSimeon Cho, general manager of Line, an app that has a strong following in Japan and South Korea: "Smartphone users download at least one of these apps to use for messaging or calls. The carriers recognise that they cannot reverse this trend and are increasing the revenue from data services."
In Singapore, Line has shown a 150 per cent growth since its launch in June 2011.
But telcos here have revised their 12GB bundled data down to 2GB or more. Thus, users pay more for additional data use.
This has made the use of such apps a concern to Mr James Ong, 28, who relies on his monthly 2GB cap to make calls using Line. The sales executive has managed to stay within his limit by using Wi-Fi to dial out.
"If I receive surcharges on my data plan, it defeats the purpose of making free calls with these apps," he said.
One downside of smartphone VoIP is the quality of the connection, which is dependent on the network strength. Mr Buse said while basic VoIP mobile calls may not consume significant amounts of data or adversely affect network performance, the way they are delivered and routed through the network is not within the control of the mobile operator.
"Hence, the quality of calls cannot be assured," he said.
An alternative to cheaper - though not free - quality voice calls is with apps such as Hoiio Phone and Skype, which offer lower talk-time rates at a fraction of what the local telcos are charging.
Since Hoiio Phone was launched in 2009, the Singapore-made service has more than 80,000 users and the number is still growing, said MrOngKok Choong, founder and chief operating officer of Hoiio. The Hoiio Phone app also does not require the other party to have the app installed.
Digital Life tests six apps that offer free voice and video calls.
This story was first published in The Straits Times on April 17, 2013
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