Axe ----automatic cross exchange.

It is mainly used as tax exchange.

Telephone Exchange - In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls. A central office is the physical building used to house inside plant equipment including telephone switches, which make telephone calls "work" in the sense of making connections and relaying the speech information.

You can buy any type of pick axe in the Grand Exchange. Located in Varrock

Describe how dialed digits are transferred from a subscriber’s telephone to the local exchange

In the Grand Exchange (which is the only place it can be bought), it's about 150k.