PDF of this tutorialFull Portability of Services
The smart card effectively breaks the link between the subscriber and the terminal, allowing the use of any properly equipped terminal and helping to realize the wireless promise of any-time, anywhere communications. In fact, subscribers need not be constrained to using voice terminals only. A variety of other mobile communications devices such as personal digital assistants (PDAs) and personal intelligent communicators (PICs) are available that may have voice communications added as an integral part of their capabilities. If these other devices are equipped for smart cards, the potential for communications is increased. Similarly, data communications applications could benefit from the security features inherent in smart cards.
International Roaming
Wireless customers often require the ability to place and receive calls when traveling abroad. For these customers, international roaming enabled by smart cards is quite valuable. For example, Ameritech, AT&T, and GTE have all instituted international roaming programs using GSM phones and smart cards. The program uses co-branded smart cards, which corporate customers bring with them when they travel abroad. Customers are given a telephone number from a GSM carrier, which allows them to be contacted in any of the countries that have international roaming agreements.
Intersystem Roaming
The incompatibility of different communications radio interfaces and authentication protocols (time division multiple access [TDMA], code division multiple access [CDMA], GSM, personal digital cellular [PDC], mobile satellite systems, etc.) requires subscribers to make choices that constrain them to use only one particular type of handset that works with only one radio interface. With a smart card, it becomes possible for subscribers to use one handset for different interfaces and protocols. This feature is already implemented among the three frequencies used by the GSM platform (900, 1800, and 1900 MHz). American National Standards Institute (ANSI) telephone industry price index (T1P1).3 has recommended standards for a user identity module, a smart card that can be used with the major radio access methods. Thus, it becomes conceivable to have current GSM smart cards modified so that they can work with a CDMA handset. For example, North American GSM operators have designed a process to which the SIM holds both the GSM and advanced mobile phone service (AMPS) authentication algorithm and data to provide authentication on both networks in interroaming situations.
Multiple Services on a Single Card
As mentioned earlier, maximum value is realized by the subscriber when multiple applications are stored on a single card (see Figure 5). A multiapplication smart card could provide access to airline reservation and ticketing systems and information networks, as well as a mobile telephone service. Considering the many cards that the average person carries these days (i.e., numerous credit cards, debit cards, employee ID cards), integrating more applications into a single card (or at least fewer cards) has obvious appeal and benefits. It is important to note that there is clear interest on the part other industries to package their services with mobile telephony. For example, research by Citibank indicates clearly that a substantial percentage of the company's customers would like to be able to conduct its banking on a variety of platforms, including wireless. Such services are already available using a standardized toolbox for smart-card application creation.
Figure 5. Smart Card—A Key to Information Services
Separation of Business and Personal Calls
The smart card allows customers to be billed separately for personal and business calls made on a single phone. For example, Airtel, a Spanish GSM operator, uses a SIM card with two sets of subscription information—one for corporate and the other for personal use. Airtel’s dual SIM cards have been well received in the corporate market.
