Maybe a little off topic, please feel free to move it if relevant.

Basically I would like to know if its possible in a house wheres theres a telephone socket in each room, that if someone makes a call you can listen to on your phone, whether you can use a modem to effectivly "intercept" all of the modems communications from another room by plugging it into your telephone jack? Is there any software for doing this?

Kinda like this I suppose

genuine modem user-------------------------->rest of world
Im just interested I think its going to be possible I just wondered if there was any software for this that any one knows of.



edit: I tryed to make my little text diagram align correctly but couldnt get it to work, the intercept arrow is supposed to be in the middle of the one between rest of world and genuine user