I live in an apartment and there are cables running from under the stairs to 5 rooms for telephones. The cable is labeled cat 5e - there are 9 cables coming into the junction box that is shown in the picture.



I want to look to using the cables to connect my router to a computer - the router is downstairs near this junction under the stairs and the computer is upstairs near a telephone point. The telephone points have RJ11 connectors.

I was also looking to have a single filter instead of filters at each phone point. 

Questions - What am I looking at in this junction box? Does there need to be two cables from this box to the telephone point upstairs if I am going to have both the telephone and the computer connected there or can this be done with just the one existing cat 5e cable?

Any help appreciated.