Voice verification is the process of verifying a person's claimed identity by analyzing a sample of that person's voice.  This form of security is based on the premise that each person can be uniquely identified by his or her voice.  The degree of security afforded by a verification technique depends on how well the verification algorithm discriminates the voice of an authorized user from all unauthorized users. 
It would be desirable to use voice verification schemes to verify the identity of a telephone caller.  Such schemes, however, have not been successfully implemented.  In particular, it has proven difficult to provide cost-effective and accurate voice verification over a telephone network.  Generally, this is because the telephone network is a challenging environment that degrades the quality of speech through the introduction of various types of noise and band-limitations.  The difficulty in providing telephone-based voice verification is further complicated by the fact that many types of microphones are used in conventional telephone calling stations.  These microphones include carbon button handsets, electret handsets and electret speaker phones.  Each of these devices possesses unique acoustic properties that affect the way a person's voice may sound over the telephone network. 
Given the inherent limitations of the prior art as well as the poor frequency response of the telephone network, it has not been possible to successively integrate a voice recognition and verification system into a telephone network.