Method and apparatus for enabling roaming of subscriber among plural mobile radio systems, using mobile equipment accepting removable subscriber identity module

Patent 5675628 Issued on October 7, 1997. Estimated Expiration Date:

October 7, 2014. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Registration of a new cordless telephone to an existing system
Patent #: 4864599
Issued on: 09/05/1989
Inventor: Saegusa , et al.

Cellular radiotelephone system, a method of protecting the data base of a visitor location register against saturation
Patent #: 5123111
Issued on: 06/16/1992
Inventor: Delory, et al.

Arrangement for obtaining authentication key parameters in a cellular mobile telecommunications switching network
Patent #: 5329573
Issued on: 07/12/1994
Inventor: Chang, et al.

Method for generating a temporary mobile subscriber identity signal (TMSI) from a permanent mobile station identity signal (TMSI)
Patent #: 5375251
Issued on: 12/20/1994
Inventor: Pfundstein

Radio having memory means for storing radio user validation code Patent #: 5404580
Issued on: 04/04/1995
Inventor: Simpson, et al.

Inventor

Hokkanen, Petri

Assignee

Nokia Telecommunications Oy

Application

No. 285123 filed on 08/01/1994

US Classes:

455/433, Home location registration (HLR) or visitor location registration (VLR) detail455/558Card control element

Examiners

Primary: Bost, Dwayne D.
Assistant: Trost, William

Attorney, Agent or Firm

Foreign Patent References

0 562 890 EP 09/13/1993
0 584 725 EP 03/13/1994
9112698 WO. 08/13/1991
94/30023 WO 12/13/1994

International Class

H04Q 007/20

Abstract

A subscriber identification module (SIM) for storing user-identities and other user specific information and thereby enabling access to the service of the radio system. One of the user identities is a Temporary Mobile Subscriber Identity (TMSI) used for user anonymity purposes by utilizing the TMSI as an alias for the actual user identity in order to avoid sending the actual user identity in the clear on the radio path. A part of the TMSI is a random number which cannot be used to identify the user/terminal without mapping information to the actual user identity, which is found in the telecommunications network entity that allocated the random number. SIM roaming from one radio system to another is possible by utilizing predetermined bits of TMSI to differentiate between different TMSI's of different systems by indicating in a uniform manner in all mobile radio systems the mobile radio system which has allocated the TMSI. The remaining bit locations of the TMSI provided in a mobile radio system-specific format. During an inter-system SIM roaming, the old TMSI will be copied from SIM and forwarded to a new mobile radio system. The new system will use the predetermined bits of the TMSI to identify the old system in order to request the actual user identity.