Patent ID: 6690798
Filing Date: 2004-02-10
Classification: H04B,H04L,H04M,H04W

Abstract:
In a mobile telephone network for providing service to a plurality of mobile stations in communication with a plurality of network stations, a first network station comprising:a mobile station identifier which identifies at said first network station the identity of a mobile station; a second network station identifier which uses said mobile station identity to determine the identity of a second network station from which a cipher variable may be obtained; a receiver which receives said cipher variable from said second network station; a former which forms at said first network station a cipher mode indication in dependence on the identity of said second network station; and a determiner which uses said cipher mode indication formed at said first network station to select an algorithm from a plurality of algorithms and uses the selected algorithm and said cipher variable to encipher or decipher traffic information signals exchanged with said mobile station during a call.