&J0      &J0 = normal single-line phone jack where the phones do
          not have lights to indicate which lines are in use.
          Such jacks include RJ-11, RJ-41S, RJ-45S.
          &J1 = multi-line business style phone jack where the
          phones have lights to indicate which lines are in use.
          Such jacks include RJ-12 and RJ-13.