Installing Router inside Electrical Closet and Hacking the Telephone Socket
For connecting the router to your phone line, you need to find the 'ISRA punt' (this is specific to the Netherlands). This is where the phone company line from outside connects to the phone wiring in your house. The cable up to the ISRA punt is owned by the phone company and you're not allowed to modify it. You are allowed to modify the wiring that comes out of the ISRA punt at the consumer end. 

There have been several standard shapes for this over the years. In older houses the ISRA punt may not even be in the metering closet. 

This KPN page helps you identify the ISRA punt: 





Does your metering closet contain an ISRA punt?