Or alternative approach #2, also involving cable + pins/tacks: move the phone point/add a second one in a more useful location, plug existing phone in there...

Tried that one. Wires need to be routed in a way that is just a pain, and will involve having to damage the (rented) house. Still won't make it very useful to use, either, as we ideally need two handsets in variable places (one of which is in another room). Alternative is just trailing it around, which usually means the kids falling over it or pulling it out of the wall.

Bleah!