To provide a simple and low-cost prepaid charging system and to promote distribution of digital contents.

When a terminal adapter 15 is connected to a line and a user designates contents, the terminal adapter 15 calls a contents delivery server 12 and is informed of the contents, and the message charging rate required for download from the contents delivery server 12. If this message rate is equal to or lower than a remaining rate stored in a memory, downloaded contents are preserved and the rate is counted down. If there is no rate remaining, the user is connected to a Q2 server 13 and is charged, after the contents delivery server 12 disconnects the line.