IDT keeps international phone calls cheap, whether you're calling Argentina or Zambia. The holding company makes most of its money through IDT Telecom, which provides prepaid and rechargeable calling cards and other payment services to customers in the US and 30 other countries. As a pioneer in international callback technology (sometimes known as call reorigination), IDT Telecom also offers wholesale termination services to reroute international calls through less expensive US exchanges. In addition, the company offers local and long distance services in 11 states under the IDT America brand.