Le site anrufer.info est-il sûr ?

This site seems seems to pursue the aim of building up a database. I tried some telephone numbers unsuccessfully, for example the "Statistisches Bundesamt" and an official telephone number of bib university. So, if you want to help the person who created the site to build up a service by collecting user-given information on telefone numbers, ok, but given that the site doesn't seem to have official input, this may take ages. For a long time the site would thus only consume the users time in fruitless searches.