Line Supervision

• Class I: Class I line security is achieved through the use of Data Encryption Standard or an algorithm based on the Cipher feedback or Cipher block chaining mode of encryption. Certification by National Institute of Science and Technology (NIST) or another independent testing laboratory is required. • Class II: Class II line supervision refers to systems in which the transmission is based on pseudo, random-generated, or digital encoding using an interrogation and response scheme throughout the entire communication, or Underwriter’s Laboratory Class AA line supervision. The signal shall not repeat itself within a minimum 6 month period and Class II security shall be impervious to compromise using resistance, voltage, current, or signal substitution techniques.