Cellular phone subsidy lock

Details Cellular phone subsidy lock Cellular phone subsidy lock

1999-04-28

2001-11-06

Eisenzopf, Reinhard (Department: 2682)

Telecommunications

Radiotelephone system

Security or fraud prevention

C455S410000

Reexamination Certificate

active

06314283

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a cellular phone subsidy lock, and more particularly pertains to a cellular phone subsidy lock which ensures that a cellular phone, sold to an end-user at a price subsidized by a cellular carrier, is activated only on the subsidizing carrier's network, and not on a competitor's network, particularly where the competitor's network likewise implements a different subsidy lock methodology.
2. Discussion of the Prior Art
The following acronyms and definitions are used throughout this patent application:
Carrier Code—code specific to one carrier;
CKSUM—Checksum for error checking;
GIM—Group Identification Mark;
ESN—Electronic Serial Number;
MIN—Mobile Identification Number (cellular phone number);
NAM—Number Assignment Module (programmed with many parameters required to operate a cellular phone such as ESN, GIM, MIN, SID, SOC);
SID—System Identification Number (carrier identifier);
SOC—System Operator Code,
In known cellular communication systems, a subscriber or user typically purchases a mobile communication phone or hand held phone or cellular phone which provides the user with access to the cellular communication system. When the user purchases the cellular phone, the phone is assigned a mobile identification number (MIN). When operating, the phone uses its previously programmed electronic serial number (ESN) and its MIN to identify itself to the cellular communication system or network (e.g. Cellular One, Bell Atlantic, etc.), and therefore, such numbers identify the user for billing and other purposes.
The Number Assignment Module (NAM) of a cellular phone stores information regarding the cellular phone, such as the MIN, the ESN, a country code, at least one SID, an optional password, and the like. Much of the information stored within the NAM is required for the cellular phone to access the carrier's system or network.
Cellular phone carriers frequently provide subsidized cellular phones to customers. As an example, a subscriber customer or end user would obtain a subsidized phone in return for a promise of continued usage of a phone system's service for a predetermined duration of time or subsidy period.
Various vendors have implemented specific methodologies regarding what procedures to implement in regards to maintaining the subsidized phone for the predetermined duration or the subsidy period.
For instance, in U.S. Pat. No. 5,864,757, issued to John P. Parker on Jan. 26, 1999, and assigned to BellSouth Corporation, there is disclosed an apparatus and method for locking and unlocking mobile telecommunication handsets or other devices.
Another such system is disclosed and described in U.S. Pat. No. 5,444,764, issued to Dawn M. Galecki on Aug. 22, 1995, and assigned to Motorola, wherein a SIM card is inserted into a radiophone for providing subscriber identification data.
For a manufacturer of a cellular phone, however, their phones may be sold to various service providers or carriers. Consequently, it would be advantageous to provide a single subsidy lock system which could be capable of implementing various phone carriers subsidy lock algorithms or methodologies or implement a subsidy lock disable or remove feature for those carriers that do not have or do not choose to use a subsidy lock algorithm or methodology.
In the carrier systems which implement a subsidy lock algorithm or methodology, it is also advantageous to enable the cellular phone for an unspecified time but terminable at a future time when used on the subsidized cellular carrier's system to thereby ensure that the subsidizing carrier receives compensation for the user's purchase of a cellular phone. Therefore, at the option of the subsidizing carrier, the subsidy lock can either be entirely disabled or only accessed so that an activation of the phone can occur.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide a cellular phone subsidy lock which ensures that a cellular phone, sold to an end-user at a price subsidized by a cellular carrier, can be initially activated only on the subsidizing carrier's network, and not on a competitor's network. Although designed particularly for an analog cellular phone, any analog or digital wireless phone (AMPS, TDMA, CDMA, GSM) can use the present invention.
It is also an object of this invention to provide a method of accessing a particular carrier's subsidy lock algorithm within the cellular phone itself.
The present invention provides a factory enabled option to ship a cellular phone in a locked state, which ensures that all activations of the phone are by the appropriate subsidizing carrier and not by unauthorized users and other carriers. Moreover, a phone provided with a subsidy lock can be disabled by the subsidizing carrier at any time.
A further object of the subject invention is the provision of a cellular phone subsidy lock in which the carrier utilizes a subsidy lock algorithm, which is capable of being implemented in software on a computer system maintained by the carrier. A secure carrier code, specific to and known by the subsidizing carrier, is programmed into the cellular phone by the phone manufacturer. The phone is programmed and shipped by the manufacturer in a locked condition, which prevents programming of any NAM (Number Assignment Module) of the cellular phone without first entering either a valid unlock code or a remove lock code, entered via the phone keypad.
At the time of phone activation and programming of a NAM, the phone's ESN (Electronic Serial Number) is entered into the carrier computer system, which executes the subsidy lock algorithm. The algorithm takes the carrier code and ESN as inputs, and outputs an unlock code and a remove lock code.
At the carrier's choice, either code may be given to the end user to be entered into the phone. The phone then executes the same subsidy lock algorithm using the carrier code programmed at the time of manufacture and the phone's own ESN, to calculate an unlock code and a remove lock code. If the code entered by the user does not match either the unlock code-or remove lock code, the phone prevents NAM programming from proceeding. If the entered code matches the unlock code, NAM programming is allowed to successfully proceed only once, and when completed the phone remains in or returns to a locked condition. If the entered code matches the remove lock code, NAM programming is allowed to proceed, and when completed the phone removes or disables the subsidy lock and goes into an unlocked condition, thereby allowing further NAM programming without entry of a subsidy lock code.
In accordance with the teachings herein, the present invention provides a solution to the following requirements:
a front-end requirement ensures that the initial activation (NAM programming) is performed only on one of the purchasing carrier's systems;
a back-end requirement ensures that once the initial activation programming is successfully completed with the unlock code, and the subsidy lock has not been removed or disabled, subsequent activations may be performed only by a repetition of the same steps;
the process is secure against another carrier attempting to reprogram the subsidized phone;
a carrier is able to disable the subsidy lock to allow subsequent activations without entry of a code;
a phone is still allowed to roam;
the subsidy lock is easy for carriers to implement for all phones from one manufacturer;
the subsidy lock feature provides two choices to optionally implement during manufacture, (1) implement no subsidy lock restriction on activation, or (2) implement a subsidy lock restriction for all activations, until disabled or removed.


REFERENCES:
patent: 4843385 (1989-06-01), Borras
patent: 5046125 (1991-09-01), Takizawa
patent: 5257412 (1993-10-01), Tomioka et al.
patent: 5259018 (1993-11-01), Grimmett et al.
patent: 5301223 (1994-04-01), Amadon et al.
patent: 5315638 (1994-05-01), Mukari
patent: 54147

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