information has more need for increased security than a message frame containing a voice payload hence the mobile unit can assign a greater weight of importance to the billing information message frame and a lesser weight of importance to the voice message frame when the subscriber identification token receives the signature signals generated from these weighted messages the cpu can assess the different weights of importance attached to each signature signal and determine a primary signature signal for only the heavily weighted signature signals alternatively the mobile unit can be programmed to convey only the u201c important u201d signature signals to the subscriber identification token this method of selective primary signature signal generation increases the efficiency of the subscriber identification token by lightening the processing load of the subscriber identification token the embodiments described above prevent unauthorized use of a subscriber 39 s account by requiring a more secure transaction between the subscriber identification token and the mobile unit since the mobile unit cannot generate a primary signature signal without knowledge of the secret uak the mobile unit that is programmed to act as a rogue shell cannot misappropriate subscriber information for wrongful purposes the embodiments described above also maximize the processing capability of the subscriber identification token by operating on a signature signal rather than a message typically a signature signal will have a shorter bit length than a message hence less time is required for the signature generator in the subscriber identification to operate on a signature signal rather than a transmission message frame as mentioned above the processing.