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SMS by termination bypass in SS7 network

• Making an international call.

The mobile network from the calling party needs to send a signal/messages called MAP_SRI to get the information of a subscriber that they need to call on an external networks.

• Sending an international  SMS

The mobile network from the calling party needs to send a signal/messages called MAP_SR4SM to get the information of a subscriber that they need to send SMS to on an external network.

Therefore the SMS-Centre only accepts or expects MAP_SR4SM, and block all others depending on configurations.

The response of these signals/messages(MAP_SRI and MAP_SR4SM) are the same, in terms of the contents of the response message.By norm, only MAP_SR4SM should be used to send SMS on foreigner or local network, Since most of network have security measure to prevent SMS attacks and frauds.

If a Fraudster/Attacker identifies a misconfiguration in your network. He/Her uses MAP_SRI to bypass SMS-Centre restrictions in order to send SMS to a network without being charged.

Since the SMS is not delivered to the SMS-Centre, the operators does not charge the sender. 

Solution for this is to make all the map traffic go to SS7 firewall and block GTs that uses MAP_SRI to terminate SMS instead of international calls.

#exit