Assuming your PC has a built in dial-up modem: connect the telephone outlet in the wall with the telephone input in the modem (card or connection on the motherboard) using a standard telephone cable. If you want to use a telephone on the same outlet (not simultaneously, of course): use a splitter.

See example cables at http://www.google.co.uk/products?hl=en&resnum=0&q=dial+up+modem+cable&um=1&ie=UTF-8&sa=X&oi=product_result_group&resnum=4&ct=title

If you've got an external modem (not built in into your PC) it will come with a cable to connect to a serial port or a USB-port on your PC. Connect the telephone port of the modem to the telephone wall outlet.

Kees


Kees