KnowRoaming is simply a sticker that can save up to 85% off your voice and data in 220 countries while you’re on roaming. As you receive all your calls abroad, you still pay for no more than local charges. It’s a great relief for those who travel a lot internationally. Basically, it automatically detects when you have left your home country and upon arrival to the destination country, it automatically switches onto a local network. With an easy to use smart app (iOS and Android), this sticker allows you to do things like register, connect your numbers, top up, check rates and many more. Requires an unlocked phone to work overseas.