TABLE OF CONTENTS One does not easily deceive Comrade Stalin.
Josif Vissarionovitch Dzugashvili
Some operators want to bar the SMS-MT from other networks, but they still want their subscribers to be able to roam in these networks, that is, to travel abroad and use their phones. This is the basic service that they feel is more important than letting them receive SMS from other networks. The reasons for barring include the following:
Economical: Operators want to allow only the sending operators, which have signed a termination fee agreement for SMS (the AA19 of the GSM Association) to reach their network for SMS services.
Economical: Operators want to reduce the cost of handling complaints from spammed customers, for which the handling costs can run to several U.S. dollars per complaint. Operators will bar other operators that they determine have supported spamming services. Or operators may use a better solution: They may install an SMS content filtering system. (We explain later how this works.)
Political: To avoid the reception of news from abroad via SMS technology that could contain politically embarrassing information.
Offering a sophisticated way of barring inbound SMS is a service that international SCCP gateway providers can offer and, hence, it's part of their business. The SMS content filtering equipment described in Section 5.3.2 can be integrated with the gateway.
All of the methods discussed next make it impossible for the SMSC to obtain the IMSI and the visited MSC of...
