It's not just in the USA that government officials use signals to contact each other; it's apparently also common in the EU. The content should remain secret.

Prince Faisal bin Farhan bin Abdullah, Minister of Foreign Affairs of the Kingdom of Saudi Arabia, received a phone call from Dutch Minister of Foreign Affairs Caspar Veldkamp, Saudi Press Agency (SPA ...

Talks between Iran and the United States over Tehran's rapidly advancing nuclear program appear ready to leave the Middle ...