The design is by Michel de Klerk, one of the most important architects of the 'Amsterdamse school'. It has a few subtle details with a message.
In a time when a telephone was not a common household item, one went to the post office to make a call. The connection was set up by an operator, who in theory cold listen in on the conversation. In the door of the 'spreekcel' (telephone booth) a stained glass window shows the telephone wires with a bird on it. The story goes that this is an eavesdropper bird, reminding the person inside of the possibility that someone might be listening in on their conversation.