Multiple Subscriber Profile (MSP)是什么？其中的profile id 1~4分別有什么作用，該如何理解這里的每個(gè)profile?

A method for allowing subscribers of a telecommunications network to change easily between sets of desired features is disclosed. The home location register stores multiple profiles of all subscribers within its serving region along with an active profile number field indicating the list of features currently available to each subscriber. Upon initial registration of the mobile station at a mobile switching center communicating with the home location register, a default profile is extracted from the home location register. Upon dialling a special code or number, a subscriber can prompt a change of profile containing a different set of features for different users of the mobile station or for different times of day or geographic areas. In this way, subscribers bypass the routine of having to contact an agent in order to add or remove features and are allowed to switch among multiple profiles at will. A personal identification number can be used to enhance the security of the profile change procedure.