A combination of numbers is not suitable to act as a trademark. Should the consumer recognize it as a trademark after all, they reasoned, it is still to descriptive. After all, it concerns a telephone information number. The fact that the European Trademark authorities did recognize the combination 1333 (appl. No. 007401961) as a trademark had no effect.
Unfortunately it is not uncommon for the Benelux authorities to go their own way. Procter & Gamble for example were able to have the shape of the packaging of toilet wipes registered as a European (shape)trademark.
Again when applying for the same in the Benelux, it was rejected, on the grounds that it did not differ to a significant degree from the rest of the market. It seems like it is easier sometimes to obtain a European trademark registration than a Benelux registration.