Scheduling a meeting between Portugal and another country takes some maths: Lisbon changes its clocks twice a year like the rest of Europe, but Brazil, Angola and much of the world do not, and the United States changes on different dates. 

This planner does the maths for you. Choose where the participants are, drag the Lisbon time and see straight away who is in office hours. It also shows the best times for a call with everyone, including in the weeks when clocks change.