How do I get the precise location (house/address)....

Of a cellphone number? Using open source methods (google etc).

all jokes aside, it would be interesting if this could be done using the proper hardware.

1. Intercept cell phone waves
2. Crack all encryption and listen to all near cell calls
3. Call phone number and initiate a conversation.
4. While conversing, have instruments locate the strongest direction of the source and calculate signal strength.
5. Repeat from multiple locations until triangulated.