Try YunGO mobile app
Poslano od Ruben Azaryan u Bangladeš forum
Try YunGO mobile app. The rate for Bangladesh is only $0.025 per minute. I am using it already several months and satisfied with its quality. Download it from their official website https://yun-go.com or find it in Play Market and App store. And as it is a mobile app you can make cheap calls not only from UK and USA but from all over the world.