Cab boxes (also known as PCP boxes) are the green metal cabinets you see by the side of the road. They are used by BT and the Cable companies to link their customer's telephone lines to the local exchange.

They come in many different shapes and sizes depending on how many phone lines they need to route. For example, in a highly populated area, there may be two or three telegraph poles that link into a large cab box. The connections inside the cab box link all of these customer lines to an outgoing cable which heads off to the local exchange.

They are often placed at road junctions, as the telco's try to site them in areas where traffic content will be high to make it harder for the phreaker to use them without being seen.

The new ones have decent locks on them, and in high risk areas, they tend to be braced with big bars and high security padlocks. It is possible to open them with the aid of a set of lock picks and a lot of practice.

Many CAB boxes still have the older style triangular shaped bolts, which are easy to open. See the Security Tools section for details on where to get the necessary tools.

The general layout inside cab boxes varies a lot depending on the age of the box and also the location. Some are very neatly wired and even have a list of the connections. Others are just a massive jumble of wiring hanging loose inside the box. The wiring mess in the latter ones can make it difficult to find a line pair quickly as the two cables making up the line pair are often not together. BT are rewiring the older cab boxes as it undoubtedly slows down their engineers when they have a problem to fix. The cable companies have very neat wiring, probably as they started fairly recently and designed their installations from scratch, unlike BT who inherited the lot from the GPO.

The boxes usually have a standard BT type socket on the inside of the door which is there for the engineer to use, although the phreaker will often find this line has been restricted to local calls only.

The phreaker will usually attach a beige box to a line pair to obtain free calls. He will dial 17070 before using a line pair to make sure that he isn't using his own telephone line to get his free call ;)

See the Test Numbers section for information on how 17070 and other test numbers are used by BT engineers.