Interception and interpretation of information from a subscriber loop phone line

The introduction of advanced error correcting protocols and developments in data compression and encryption have made the manual task of interpreting intercepted information nearly impossible. The seven layered open systems interconnection (OSI) model for communications system architecture is used as a basis to explore some of the many complex issues in data interpretation. The basic functions of each layer of the OSI model are discussed and examples of commonly encountered protocols used on the public switched telephone network are provided. The discussion is then extended to include issues of interpretation of the file level. One suggested solution to the problem of interpreting intercepted data is to develop a master database of all of the protocols that could be implemented at each level of a communications session. Such a database could be used to assign priorities for efforts to develop software tools for automating the interpretation function. This database could be used to evaluate and compare the various interception systems available in the market.<>