Everything worth knowing, nothing that isn't.
How SS7 and Diameter signaling security works
A signaling firewall sits inline at the interconnect, inspecting every inbound SS7 MAP and 4G Diameter operation before it reaches the HLR, HSS, or MSC. Each message is checked against GSMA category rules, the sender's global-title reputation, and plausibility (does this roaming update make geographic sense?), then passed, rate-limited, or dropped. Every decision is logged for audit. See /answers/what-is-ss7 and /answers/ss7-map-explained.
The threats it stops
SendRoutingInfoForSM harvesting that reveals a subscriber's IMSI and serving MSC for location tracking; ProvideSubscriberInfo and AnyTimeInterrogation location queries; SMS interception via rogue MT-ForwardSM; and Diameter equivalents on 4G. See /answers/ss7-map-send-routing-info-for-sm, /answers/ss7-map-provide-subscriber-info, and /answers/diameter-s6a-explained.
The GSMA standards: IR.82, IR.88, FS.07 and FS.11
GSMA IR.82 sets SS7 security implementation guidelines and the Category 1/2/3 message classification; IR.88 covers LTE/EPC Diameter roaming; FS.07 defines SS7 monitoring and FS.11 the SS7 interconnect security controls. Together they tell operators which inter-network operations to block, rate-limit, or allow by peer. See /answers/gsma-fs07-fs11-signaling-firewall.
Benefits for the operator
Subscriber protection against tracking and interception, regulatory and GSMA compliance, a tamper-evident signaling audit trail, and the ability to correlate signaling with A2P traffic to catch fraud that spans both planes. BroadNet pairs the signaling firewall with SMS-firewall and CDR intelligence for one policy view. See /operators/ss7-firewall and /platforms/signaling-cdr.
Limitations and operational realities
A signaling firewall is only as good as its category rules and reputation feeds — over-blocking breaks legitimate roaming, under-tuning leaks attacks. It must span both SS7 and Diameter because networks run hybrid 2G/3G/4G cores, and it cannot see inside encrypted 5G service-based signaling, which needs its own SEPP controls. See /answers/what-is-sigtran.
SS7 firewall vs SMS firewall — what's the difference?
An SS7 (signaling) firewall polices the network control plane — MAP and Diameter operations — to stop location tracking and interception. An SMS (A2P) firewall polices the application layer — message content, sender IDs, and SMPP delivery — to stop smishing and grey routes. They defend different layers and are strongest deployed together. BroadNet delivers both. See /operators/sms-firewall and /operators/ss7-firewall.