Call charge transfer is a freephone service (FPH). It is a service feature ofISDN and a value-added service where the call charges are paid by the service provider. The subscriber does not pay any charges for this value-added service. There are national and international freephone services. The service code defined by the International Telecommunication Union( ITU) for international Freephone services has the country code (0)800.
Freephone is also a service in intelligent networks defined in the Capability Set( CS).