Abstract: A wireless communications network, a home location register and a method are provided that have an improved signal strength arbitration scheme which can ensure that a mobile terminal is registered at the most appropriate mobile switching center. In particular, the home location register includes a database coupled to a processor capable of implementing a signal strength arbitration scheme that assigns a provisional quality value to a registration signal that was received from a mobile switching center which failed to include a quality parameter within the registration signal, wherein that mobile switching center may now be considered and possibly registered as the most appropriate mobile switching center to process a wireless call of a mobile terminal that broadcasted a registration access signal to a plurality of mobile switching centers.

Abstract: An authentication process is triggered when a subscriber of a GSM-type cellular-phone-network service attempts a call. In this process, an encrypted result, or a “signed response,” previously stored in the subscriber's cellular phone, is transmitted to a Mobile Switching Center (MSC), and a Home Location Register (HLR) in the MSC compares the signed response to an encrypted result previously stored at an Authentication Center (AuC). If the signed response matches the stored encrypted result, the call is allowed to proceed; otherwise, access to a telephone network is denied. Proceeding with the call, the AuC generates a random number and derives a new encrypted result by means of a ciphering algorithm, e.g., a CAVE algorithm, using the random number and the subscriber's unique key previously stored in a database at the AuC.

Abstract: In a method for dynamically updating a cellular-phone-unique-encryption key previously stored in, and common to, each of a cellular phone and an associated home location register (HLR) for providing security in a cellular-phone-network operation, a random number and shared secret random data generated at least partly based on the random number are transmitted and verified between the cellular phone and the associated HLR. A previously stored version of the cellular-phone-unique-encryption key is then dynamically updated in both the cellular phone and in the HLR by independent calculations based on an algorithm using the shared secret random data and the previously stored version of the cellular-phone-unique-encryption key. In this manner, the cellular-phone-unique-encryption key is dynamically updated as desired, e.g.

Abstract: Catheters formed from polyurethanes containing sufficient halogenated moieties in the polymer structure to make the polyurethanes radiopaque are disclosed. Such polyurethanes can be prepared by employing halogenated diols and/or halogenated diisocyanate reactants. In preferred cases, the catheters are optically transparent in addition to being radiopaque.