Stockholm-based Rebtel has been in operation since 2006 and passed 20 million active users in December 2012. The company earned revenues of $80 million last year, and has seen a 250% increase in app downloads and paying users since 2011, with overall users growing currently at a rate of 500,000 each month.

We had the opportunity to interview Rebtel CEO Andreas Bernström regarding the company’s goals throughout the 2013 year as the world’s second-largest mobile VoIP company behind Skype keeps nipping at the heels of its larger competitor. Needless to say, it looks to be yet another exciting one for the communications firm.

Aside from cheaper calling rates and a great 98% approval customer rating, how does Rebtel differentiate itself from other VoIP services and applications?

“The fact that we do call termination over data and local minutes, cheap international SMS as well as free app-to-app calling all wrapped into a single easy to use package is our greatest asset in terms of differentiation. There’s a way to call with Rebtel regardless of who you want to call and where you are in the world. Cheap international calls is our core business and it has taken a long time for us to get where we are today in terms of the quality and low rates we offer. Quality, reliability and low rates are all aspects of the Rebtel calling experience also set us apart from everything else out there.”

What were some challenges you faced in 2012? How did you meet those challenges?

“Maintaining a consistent growth rate, to meet our overall company goals, retaining users in an increasingly crowded and competitive landscape are a few that we’ve had going into it and succeeded in accomplishing. For most of 2012, our resources were dedicated to improving the quality of the service, which amounted in the release of HD Voice for our iOS and Android offerings. The technology is based on iSAC, which is a wideband codec used in different types of VoIP apps. It became available as an open source technology as a part of the WebRTC project when Google acquired GIPS in 2010 and one of its many benefits is its ability to adapt to the users bandwidth conditions and not be dependent on a high-speed data connection. It’s really made the world of a difference.”

What challenges would you like to overcome in 2013? What do you hope to accomplish by year’s end?

“More of the same, basically. Keep pushing our rates, make our offerings even better than they are today, work on quality, usability, design and maintain our growth levels.”

Are there any significant features or changes planned for 2013 that you can tell us about?

“We definitely have some cool stuff lined up for 2013, but none that I can speak on at this time.”

Does Rebtel plan to expand beyond VoIP to services such as GSM SIM Roaming service in the near future?

“We constantly look at the overall needs and wants of our target group of users as far communication habits are concerned. We try to have a holistic approach that isn’t necessarily limited to when a Rebtel user makes an international call, but at the bigger picture and how we fit into their mix of communication apps. Whether or not that includes a roaming solution remains to be seen.”

One feature that Mr. Bernström feels many Rebtel users may overlook is its unique “Keep Talking” feature. Keep Talking allows users who are talking over Wi-Fi to switch to the mobile network at a moment’s notice. The app will prompt you to tap the Keep Talking button on the call screen to keep the call conversation going seamlessly. This feature is very useful, especially if you’re in a hurry and have to get somewhere or your connection to your Wi-Fi network goes down for some reason. The feature worked perfectly even on our older Android device.

Rebtel is currently available for iPhone, iPad, Android (phones and tablets), Windows Phone, and desktop computers, making it one of the most easily accessible VoIP applications on the planet.