The statistics of cell loss and misrouting due to transmission errors in asynchronous transfer mode (ATM) or cell-based systems, which result in unreliable data transmission and thus in a degradation of service quality, are developed. Results indicate that it is essential to use a decoding scheme for the virtual channel identifiers of a cell in order to satisfy the expectation of the subscriber with respect to transmission reliability and data security. The models of connections, exchanges, and transmission in the cell-based systems are presented.