FS.40 (5G Security Guide)

In telecom networks, GSMA FS.40 is the high-level operator security guide for 5G, covering the SBA, network slicing, virtualization, edge computing, and interconnect, and pointing to detailed documents such as FS.36 for inter-PLMN security.

Categories: Core NetworkRoaming and InterconnectProtocols and Standards

FS.40 in context

The mobile core is where subscriber sessions, mobility and policy live. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF. Core exposure is the difference between a single-subscriber leak and a fleet-wide breach.

Roaming and interconnect are where two operators, often with an IPX or GRX carrier in between, exchange signaling and user-plane traffic. Trust boundaries here are the primary attack surface for location tracking, SMS interception and fraud, which is why GSMA now mandates SEPP with PRINS on 5G interconnect.

To place FS.40 in the wider telecom-security picture, review PRD, NESAS, SEPP, Defense in Depth, GSMA SCAS and NDR.

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