Since 1996 there has been a revolution in German telecommunications. With the deregulation of the market, a plethora of new phone companies has emerged and competition has pushed prices down dramatically. At the same time the standard of service has improved: ISDN lines are widely available and itemised billing is a matter of course.
To get the most out of the telecommunications market though, you have to shop around. A number of internet sites will help you to find the cheapest provider for your call be it mobile, national or international. It is worth taking the time to find a cheap carrier. A 10 minute call to Australia for example will cost around DM1,00 with the cheapest providers and over DM15,00 with DT.
The best way to get these sort of discounts is "call by call." This means that you do not bind yourself to one carrier. Rather you dial a five digit prefix before each long distance call. By doing this you choose the carrier you wish to call with. Despite the fact that you might use 5 or more carriers in the course of a month, all services have a consolidated billing service organised by DT so you only have one bill to pay.
To find out which company has the cheapest tarifs for the call you want to make, visit billiger-telefonieren.de (German only).