Sony Ericsson Sim Lock Patent Info

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I've located an interesting patent on the simlock security system on sony ericsson phones:

http://www.freepatentsonline.com/6785537.html

United States Patent 6785537

excerpts from patent:

"There are five personalization categories that a network operator can choose among when purchasing GSM mobile equipment from a manufacturer. The network operator can instruct the manufacturer to enable any of the personalization categories. The personalization categories, in no particular order, include network personalization, network subset personalization, service provider personalization, corporate personalization, and SIM personalization. Network personalization allows the network operator to personalize mobile equipment so that it may only be used with that particular network operator's SIM cards. Network subset personalization is a refinement of network personalization that allows network operators to limit the usage of mobile equipment to a subset of SIM cards. Service provider personalization allows a service provider to personalize mobile equipment so that it may only be used with that particular service provider's SIM cards. Corporate personalization allows a corporate customer to personalize mobile equipment for employees or customers so that the mobile equipment may only be used with the company's SIM cards. SIM personalization enables an end user to personalize their mobile equipment so that it may only be used with a particular SIM card.
There are five corresponding control keys (authorization codes) that toggle the aforementioned personalization categories “on” and “off”. The control keys are termed NCK for network control key, NSCK for network subset control key, SPCK for service provider control key, CCK for corporate control key, and PCK for personalization control key. The control keys are randomly generated by the manufacturer and permanently associated with each piece of mobile equipment. In addition, the mobile equipment includes hardware and software protection mechanisms that prevent unauthorized disabling or enabling of the personalization categories. The purpose of the control keys is to allow an authorized person to enable or disable a particular personalization category. If one or more personalization categories have been enabled, then the mobile equipment will only function when a SIM card having matching personalization data is inserted into the mobile equipment. "

"Most network operators do not use the service provider personalization or corporate personalization categories. As a result, the network operators do not provision their SIM cards for these categories. Specifically, the Group ID 1 (GID1) file pertaining to service provider personalization and the Group ID 2 (GID2) file pertaining to corporate personalization are not provisioned on the network operator's SIM cards. Moreover, the GID files residing on SIM cards are tamper resistant as well. GID files cannot be created or modified without SIM card administrative codes which are kept in confidence by the network operator. The present invention takes advantage of the non-enablement of one of these personalization categories. For illustrative purposes only this disclosure will be described in the context of the service provider personalization category.
When the network operator places an order for a quantity of mobile equipment, the network operator can specify that the manufacturer enable service provider personalization in addition to network personalization 20 . Thus, the mobile equipment can not function in the network unless and until both categories have been validated. Network personalization will remain enabled on the mobile equipment and the SIM card must have a matching identifier. Service provider personalization, however, is initially enabled but is disabled via entry of the proper service provider control key (SPCK). Once service provider personalization is disabled it is never prompted for again and becomes moot. "