To help with the growing amount of resistance work they are doing, the Ten Booms have their phone line re-installed for the first time in the three years since the German invasion. Although they are very happy to have a phone again, they keep the ringer on low: they are concerned not to draw attention to any phone calls.

The family also cannot be sure the phone isn't being tapped, with the Gestapo listening in on their calls. Therefore, they devise a coded system for speaking. Since the Ten Booms have a watch repair shop, their code involves watches. This makes sense, as people would naturally call the shop with problems and questions about their watches.

Therefore, the phrase "a watch with a difficult face" became a code for a Jewish person who was difficult to hide because of his or her facial features looking too stereotypically Jewish. A child's watch not being reparable meant a Jewish child who was being hidden had died.

Those who answered the phone had to be alert for hidden messages: while the watch repair shop was a center of the resistance and helping the Jews, it was also a working repair job. The Ten Booms had to distinguish between different types of callers.