Ranking First in International Phone Call Division of 2014 App Award Korea. 2015 Master Consumer Confidence of Korea Brand Awards. Did you know that the 2002 legendary figure of World Cup, Coach Gus Hidink, used OTO? OTO Free International Phone Calls app is used by more than 5 million people. [Main Functions]. Free International Phone Calls- You may place free international phone calls to the United States, Canada, Japan, etc. to 94 countries in Korea. (However, free phone calls are available according to the payment plans of smart phones. ). Why OTO Free International Phone Calls? 1. OTO Frree International Phone Call is free because it does not incur cost for any international phone calls placed. 2. You may use international phone calls via the local voice phone bills, so no worries. 3. Unlike other services that offer free service to a limited range of countries, OTO offers free phone calls to all 94 countries. Even if it is not one of the designated countries for free service, you're in good hands as long as you're using global OTO app. Install the global OTO app if the country that you would like to call is not listed as one of the countries under free of charge service areas. You can use international phone call service for around 250 countries worldwide of the highest quality for the lowest price imaginable. OTO Global App offers voice all service to 45 countriies worldwide, and as long as your data is connencted, you may call any country anywhere in the world. If you encounter any inconveniences using our service, please do let us know. We are always all ears for your valuable opinions. website: www.otocall.com- call center: +82-2-16000546Free International Call, Free, Call, Smart, Intl call, Prepaid international call, Global, OTO, Cheap, low price.