[Wishiknewmore]

Graham,
The switch is spring loaded so it rests in the middle, but against the up position, I also thought it could have been for tapping out some form of code but then would have been loaded again the bottom?

Bill, thanks for the link, that is where I found what it was

Although I initially dismissed using it with the land line, If I found a suitable AC bell box could it be used to receive calls?

Thanks Philip