Home intercom, door answering system which wont...

Question

I have just moved into a house which has a basic intercom system built into the wiring of the house. unfortunately it seems to be pretty dead.i have opened up the phone handset inside the house and it all looks pretty well connected. I opened up the outside intercom and it looks fine though there did seem to be two loose (ish) wires hanging free. I also tracked the wiring into the house, and it seems to have its on control box, beside the mains electric box. do you know any basic fixes for this type of system?