Enabling UPNP means any application (or a virus) can silently open ports in your router.
Green Granite - that is the URL I posted too. They have a dual-band booster
for about £200.
Re diverting Voda calls... I also would like to have a solution for Giffgaff, and Virgin PAYG, used by others in the house.
In fact the booster would not be in the house (due to wiring etc issues). It would be in an outbuilding and, assuming the output aerial is directional, it would be pointed towards the house.
I also don't want to provide a service for a nearby pub, whose customers are having to stand outside to make calls, which I am sure the owners are not unhappy about