Wireless pre-paid Phone cards distributing system based on SMS

There are so many kinds of pre-paid phone cards from several telecom service providers. But how to distribute them in a safe, prompt, and cheap manner seems to be a challenge. This paper proposes a wireless distributing system based on SMS (short message service) which consists of a database centered Server and several mobile hand-held terminals. The Server's structural scheme and the data consistency problems confronted and their solutions are discussed. The terminal which is manipulated by an embedded system provides a convenient User Interface to the agents and it communicates with the Server through SMS in an interlocked protocol. To reduce the data redundancy in the transmission, an encoding algorithm is presented, and 8 pre-paid phone cards could be sent in one Short Message.