i was wondering if there is a way u can listen to a 900 mhz cordless phone conversation from some type of scanner , Yes and no. If it is spread spectrum then without a spectrum analyzer with an Audio Demod and some other stuff, you can't monitor it :-)

If its a straight non spread spectrum non digital signal then yes you can, just search the allocated frequencies.

and be able to pinpoint the exact phone? a couple of good yagi antennas, some signal strength meters, and wide band recievers should help you. Look up "Fox Hunting" and talk to some local hams, they should be able to help you out.

can u bugg a cordless phone without being seen? I won't insult you by asking if you are na idiot, but please try to come up with sensical questions friend.

is there listening devices that can go thru houses to hear? I could not even start to parse this one folks...