The number 110 connects you to the police control center free of charge, whether from a landline or cell phone.

When dialing the emergency number 110 with a cell phone, please note that you will not automatically reach the local control center.

On the phone, state WHO is calling, WHAT has happened and WHERE it has happened. Do not simply hang up, but wait for further questions! 
Speech or hearing impaired people have the option of sending an emergency fax to the fax number 110.
 

Further information and the emergency fax numbers of other police authorities in North Rhine-Westphalia can be found here.