This is the one app you should use to make phone calls when you're traveling abroad

As if traveling internationally wasn't expensive enough, even a few seconds on the phone can really add up, which is why savvy travelers know to download an international calling app.

However, the dizzying amount of apps is enough to make anyone want to just pay the international roaming in exasperation.

And while most people know about popular apps like Skype and Viber, the app we think is best hasn't been as widely discovered.

The best app to make international calls is Truphone.

Somehow, Truphone has been collecting awards left and right, while remaining under the radar.

The free app, widely considered Skype's biggest rival, lets you make free international calls over Wi-Fi, 3G and 4G to other Truphone users. However, you can also use the app to make super cheap calls to the less enlightened in your circle who don't have Truphone (yet).

Calling rates to both landlines and non-Truphone cell phones are much lower than those of competitors (0.04 cents a minute to a German cell phone versus Viber Out's 5.9 cents/min; free when calling a landline versus Viber's 1.9 cents/min). Plus, before making any call to a non-Truphone number, the app will tell you what rate you're working with, as well as what the call quality will be. The app automatically connects to your app store, making getting phone credit a breeze.

Truphone also ensures the best call quality by searching the nearby Wi-Fi networks to select the best network for your call.

I called my mother in Vienna to test the app, and added credit with my iPhone touch ID, which was very easy. The call was indeed crystal clear. My only complaint was a weird musical ring and a voice breathing the word "Truphone" as I was waiting to connect.

Truphone also has a service called TruSIM, which gives you your very own local phone number. What this means is that you can not only get local rates in over 200 countries, locals can call you at no extra cost. In the US, UK and Australia, calls, texts and MB used are all a flat rate of 0.09 cent per minute.

TruSIM is an actual SIM card that costs $29.99, but lets you have up to three local numbers on it (each additional number will set you back $8 a month), and automatically uses the local number of the country you are in when you place a call.

This app is ideal for frequent travelers. And while TruSim may cost a little extra, it's also well worth it.

Cost of app: Free
Does it need Wi-Fi: Yes
Can it call landlines: Yes

Download it here.