You can also connect to

Linkedin is a social Media website for Professional People.
It does not list German phonenumbers like historic Whitepages
but profiles of individual people.

Connected to Linkedin you can send messages
to people from Germany you found.

As of 2021 June 28 12.350.000 people from Germany
are connected to Linkedin.

Linkedin was founded by Reid Hoffman in California in 2002.
The platform came to the web 2003
2016 Linkedin was acquired by Microsoft.
More on the history of Microsoft
on the Brand Portal