- Adds 8 digital ports to the existing capacity.

- This card can add 8 more extensions, required you use all
  digital phones in DXDP mode.
  The digital phones should be Panasonic
  proprietory phones such as
  KX-T7531*, KX-T7533*, KX-T7536* KX-T7565*,
  KX-T7668, KX-T7630, KX-T7633, KX-T7636.