SS7 vs Diameter
SS7 and Diameter are the two dominant signaling protocol families in mobile networks. SS7 (Signalling System No. 7) underpins 2G and 3G interconnect; Diameter succeeded it as the LTE/4G signaling layer with an IP-native design. Both remain in production and both are actively exploited.
| Attribute | SS7 | Diameter |
|---|---|---|
| Generation | 2G / 3G | 4G / LTE |
| Transport | MTP / SCTP (SIGTRAN) | SCTP / TCP over IP |
| Message unit | MAP / CAP TCAP dialogue | Diameter AVP-based command |
| Roaming interface | International SS7 interconnect | S6a / S9 over IPX |
| GSMA firewall spec | FS.11 (categories 1, 2, 3) | FS.19 |
| Typical attacks | AnyTimeInterrogation, SRI-SM, UpdateLocation abuse | IDR, PUR, CLR abuse; S6a subscriber tracking |
| Encryption | None natively | Optional IPsec / TLS on the transport |
| Authentication | Point-code trust model | Origin-Host / Origin-Realm trust |
Verdict
Diameter is not "SS7 fixed" — it is a re-implementation of the same trust model over IP. Operators need signaling firewalls on both stacks (FS.11 for SS7, FS.19 for Diameter) plus GTP filtering (FS.20) for the user plane. Retiring SS7 is a multi-year project; both protocols will coexist until 5G SA is universal.