IBM Technical Disclosure Bulletin, vol. 34 No. 1, Jun. 1991, New York, US pp. 331-338, XP000210235 Anonymous: "Method of Providing Encryption/Decryption for integrated Services Digital Network Telecommunications." |
International Switching Symposium 1987: `Innovations in Switching Technology`. Proceedings (Cat. No. 87CH2431-5), Phoenix, AX, USA, Mar. 15-20, 1987, New York, NY, USA, IEE, USA, pp. 863-869 vol. 4 XP0002017713 O'Higgins B et al: "Encryption and ISDN-a natural fit". |
ICASSP-94. 1994 IEEE International Conference on Acoustics, Speech and Signal Processing (Cat. No. 94CH3387-8), Proceedings of ICASSP '94. IEEE International Conference on Acoustics, Speech and Signal Processing, Adelaide, Sa Australia, 19-22 Apr. 1, ISBN 0-7803-1775-0, 1994, New York, NY, USA, IEEE, USA, pp. II/425-8 vol. 2, XP00528508 diez-del-rio 1 et al: "Secure speech and data communication over the public switching telephone network". |