Claims:1. A method for updating a preferred roaming list of a user identity module card, the method comprising:
reading preferred roaming list updating data;
packing the preferred roaming list updating data in a preferred roaming list updating text message; and
writing the preferred roaming list updating text message into a text message file of the user identity module card.
, Description:TECHNICAL FIELD
The present invention relates to a method for updating a preferred roaming list (PRL) of a user identity module (UIM) card.

BACKGROUND
In a CDMA communication system, a preferred roaming list (PRL) file, which contains a list of operators in other countries signing network roaming protocols with local operators and related network parameters, is stored in a user identity module (UIM) card of a mobile communication terminal. Thus, a mobile communication terminal may achieve network roaming by using data in a PRL file.
Within a course of development of communication system, during instrument testing, especially during radio frequency testing, in most cases it is only required to set a PRL in a UIM card to make the PRL match an instrument. That is, it is required to set a PRL file according to parameters of the instrument.
Currently, there are two methods for setting a PRL file: one is to update a PRL file by receiving a PRL updating text message from a mobile operator, and the other is to write a PRL file into a special white card using an interface provided by a UIM card manufacturer.
The UIM card used in the first method must be a card activated in a live network, and cannot be a defaulting card or a discarded card. In addition, in such a way, a PRL can only be updated to the latest version of the live network rather than specified contents. Thus, this method is not applicable to instrument testing.
Although the second method is capable of specifying PRL files, there exist the following problems: firstly, white cards used are high in cost, with each white card usually costing about 100 yuan; and secondly, some UIM card manufacturers may not be willing to disclose an interface for modifying PRL files or to provide corresponding modification permissions.
Thus, there is desire for a method capable of setting a PRL file in a UIM card at low cost.