The Subscriber Identity Module (SIM) concept is widely used in many mobile communication systems. some limitations and considerations of using SIM significantly reduce the availability and accessibility for the public in the wireless communications. The idea of using phone card for the public telephones is introduced for the mobile communications in this study. This new application is proposed to improve, in the meantime, to contain the merits of SIM. Major technical issues for using phone card includes the location tracking of the user, authentication of the phone card, and the billing shceme. In this study, three authentication approaches are also presented.
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