Method of charging for additional services, and additional-service communication system

Disclosed is an additional-service communication system in which an additional service for which a request has been issued by a subscriber apparatus is provided to the subscriber apparatus from a provider apparatus by cells via a transmission line. In the communication system, a transmission apparatus is provided between the provider apparatus and the subscriber apparatus. The transmission apparatus generates charge metering cells commensurate with amount of additional-service cells in regard to each subscriber apparatus and transmits these cells to the provider apparatus and subscriber apparatus via the transmission line. The provider apparatus counts the charge metering cells in regard to each subscriber apparatus and calculates the charge due from each subscriber apparatus. The subscriber apparatus counts the charge metering cells, calculates the charge due and displays this charge.