He should just go to CompGeeks and get their 1000 ft roll deal with crimper/tester, RJ-45 ends, and just run it the entire length and be done with it. The only iffy thing is the UV, then run it in a conduit to protect it.
You can get couplers for the cat5 cable for under $10.00...
only problem there is gonna be the weather... they do make boxes/connections that are rated for outdoors..
I think that if you put your switch outside in a covered box eventually corrosion would become a problem... heating/cooling/moisture are all factors..
My advice - buy or make a longer cable keep the electronics inside..
A few more thoughts :
If you cant get at it from the attic, have you considered following the pipes? - drain pipes usually have pretty big holes...
Have you thought about drilling some holes in the corner of the floor/ceiling and just pulling the wire thru... they make tracks that you can use to cover it or you could build a box - of course this would mean cutting an end off and recrimping to keep the holes small but its an option...
Your phone problems could be from the fone company, have them put a surge supressor outside the house on the box.. check the grounding on the box. - aluminum siding conducts everywhere!
