In general you will need one filter for each phone device (including normal phone handsets, Sky TV Decoders, alarm panels etc) you have in the house.
When you purchase a router from us, it will normally include at least one filter.
If you need more, come into our Napier customer hub and we'll hook you up.
We can courier out additional filters too, just give us a call on 0800GETNOW (0800438669).
Can't wait? You can also purchase filters from many electronics stores such as Harvey Norman, Noel Leeming, Jaycar etc.