4.1.10 Outbound transit traffic (relayed by SRF)

29.2043GPPArchitecture, functional description and protocol detailsRelease 17Signalling System No. 7 (SS7) security gatewayTS

This scenario is shown in figure 4.1.10. The message (originally destined for the PLMN) is originated at a NE outside the transit PLMN. It may transit several transit nodes outside the transit PLMN (including an SS7 Security Gateway), an SS7 Security Gateway of the transit PLMN in inbound direction (see Clause 4.1.2), several transit nodes inside the transit PLMN, and an MNP-SRF which replaces the SCCP called party address of the message before it reaches the SS7 Security Gateway in outbound direction. This SS7 Security Gateway recognizes that the message was relayed by an SRF by analyzing the SCCP called party address and protects the message with the relevant Security Association. The message may then transit several transit nodes outside the transit and destination PLMN (potentially including an SS7 Security Gateway) before it reaches the destination PLMN.

Figure 4.1.10: Outbound transit traffic (relayed by SRF)