Cellular phone subsidy lock

• US 6,314,283 B1
• Filed: 04/28/1999
• Issued: 11/06/2001
• Est. Priority Date: 04/28/1999
• Status: Expired due to Fees

• Current Assignee: NEC Corporation of America (NEC Corporation)
• Original Assignee: NEC America Inc (NEC Corporation)
• Inventors: Fielden, Ronald L.
• Primary Examiner(s): Eisenzopf, Reinhard
• Assistant Examiner(s): Mehrpour, Naghmeh
• Application Number:
  US09/300,954
• Time in Patent Office: 923 Days
• Field of Search: 455/410, 455/411, 455/418, 455/515, 455/419, 455/420
• US Class Current: 455/411
• CPC Class Codes: H04M 1/673 the user being required to key in a code
• CPC Class Codes: H04W 12/08 Access security
• CPC Class Codes: H04W 12/48 using secure binding, e.g. securely binding identity modules to devices, services or applications
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

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. A secure carrier code, specific to and known by the subsidizing carrier, is programed 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 the NAM (Number Assignment Module) of the cellular phone without first entering either a valid unlock code or a valid remove lock code. At the time of phone activation and programming of the NAM, the phone'"'"'s ESN (Electronic Serial Number) is entered into the carrier computer system, which utilizes the ESN and carrier code to execute a subsidy lock algorithm which outputs an unlock code and a remove lock code. At the carrier'"'"'s choice, either code is 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 it'"'"'s own ESN, to calculate the unlock code and the remove lock code. If the code entered by the user matches the unlock code, NAM programming is allowed to proceed only once, and if the entered number matches the remove lock code, the phone removes the subsidy lock completely.

Claims

1. A method of processing a cellular phone having a subsidy lock option to ensure that the cellular phone, sold to an end-user at a price subsidized by a carrier, is activated for use only on a network of the carrier, comprising:

a. agreeing between the carrier and a manufacturer upon a carrier code associated with the carrier and upon a subsidy lock algorithm associated with the carrier;

b. storing by the manufacturer the carrier code into a memory of the cellular phone and programming the subsidy lock algorithm into the cellular phone;

c. placing an order by the carrier with the manufacturer for the purchase of subsidy locked cellular phones, wherein the manufacturer sets a subsidy lock flag which places the cellular phone in a locked condition thereby preventing programming of a number assignment module (NAM) of the cellular phone;

d. activating the cellular phone for use by the end-user by;

1. executing the subsidy lock algorithm on a computer of the carrier using an electronic serial number (ESN) of the cellular phone and the carrier code for generating either an unlock code or a remove lock code or both;

2. Entering into the cellular phone an entry sequence and either the unlock code or remove lock code, wherein the cellular phone calculates a calculated unlock code or a calculated remove lock code or both, and compares the entered code to the calculated unlock code or the calculated remove lock code or both, and upon a match of the entered code and the calculated remove lock code or the calculated unlock code, permits NAM programming to proceed; and

3. programming the NAM to enable the cellular phone to be used on the carrier'"'"'s network.

2. The method of claim 1, wherein after the step of programming the NAM, the cellular phone confirms that the NAM programming has completed successfully;

and thereafter compares the entered code to the calculated remove lock code, and if the entered code and the remove lock code match, then the cellular phone removes the subsidy lock flag set by the manufacturer, thereby enabling additional NAM programming.

3. The method of claim 1, wherein the step of entering the ESN of the cellular phone includes entering only place specified digits of the cellular phone'"'"'s ESN for use by the algorithm.

4. The method of claim 1, wherein the step of entering the carrier code of the carrier includes entering only place specified digits of the carrier code for use by the algorithm.

5. The method of claim 1, wherein the step of programming the NAM on the carrier'"'"'s network includes using a SID which corresponds to the carrier.

6. The method of claim 1, wherein the step of programming the NAM on the carrier'"'"'s network includes using a SOC which corresponds to the carrier.

7. The method of claim 1, wherein the step of entering an entry sequence includes using a key sequence which permits the phone to identify a specific carrier.

8. The method of claim 7, wherein the key sequence identifies a carrier specific algorithm.

9. The method of claim 7, wherein the key sequence is #ID# and wherein #ID# identifies a specific carrier.

10. The method of claim 1, wherein the step of entering an entry sequence includes transmitting the unlock code to the cellular phone.

11. The method of claim 1, wherein the step of entering an entry sequence further includes the step of incrementing or decreasing a count and comparing that count to a fixed value, and if the fixed value is exceeded, disabling the cellular phone from any further NAM programming.