The absence of security in Signalling System No. 7 (SS7) networks is an identified security weakness in 2G systems. This was formerly perceived not to be a problem, since the SS7 networks were the provinces of a small number of large institutions. This is no longer the case, and so there is now a need for security precautions. For 3G systems it is a clear goal to be able to protect inter-network SS7 signalling protocols. The protection is done by security gateways which are located at the network border. As a consequence intra network SS7 signalling is not protected and network elements other than Security Gateways are not impacted.

The present document provides functional description of the SS7 Security Gateway. The document covers also network architecture, routeing considerations, and protocol details.

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.

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