# SIGTRAN — SS7 over IP explained

> SIGTRAN is the IETF/3GPP family of protocols that transports SS7 signalling over IP networks (typically over SCTP, not TCP, for ordered multi-streamed reliable delivery). It replaced the dedicated TDM/E1 SS7 links that operators used to lease at huge cost, letting SS7 ride the same IP backbone as everything else. Almost every operator-to-operator SS7 link in 2026 is in fact SIGTRAN underneath.

- Canonical URL: https://www.broadnet.me/answers/what-is-sigtran
- Language: en
- Last reviewed: 2026-05-28
- Publisher: BroadNet (https://www.broadnet.me)

## What it actually does

SIGTRAN preserves the SS7 application protocols (MAP, CAP, ISUP, TCAP, SCCP) and replaces only the lower transport layers. Where classic SS7 used MTP1/2/3 over E1 links, SIGTRAN uses adaptation layers (M2PA, M2UA, M3UA, SUA) over SCTP over IP. From the application's perspective — an HLR, an SMSC, an MSC — nothing changes. From the network's perspective, everything changes: signalling now rides leased lines, MPLS, or even the public internet (typically with IPsec).

## Why it matters commercially

SIGTRAN is why a new operator can get signalling connectivity in days instead of months. Provisioning a SIGTRAN association requires IP transit and an STP peer agreement; provisioning an old-school SS7 link required physical E1 circuits, line drivers, and a months-long telco install. SIGTRAN reduced SS7 transport cost by an order of magnitude, which is why SS7 message volumes per operator grew 10-100x between 2005 and 2015 — and why SS7 firewalls became a necessity. BroadNet operates SIGTRAN STPs in MENA data centres for SS7 interconnect (/operators/ss7-firewall) and global signalling reach.

## Latency, scale, and compliance angle

SIGTRAN latency over a dedicated fibre IP path is comparable to TDM SS7 (single-digit ms within a country, 50-150 ms intercontinental). SCTP's multi-homing means a SIGTRAN association can survive a single ISP failure without dropping signalling. Scale: a single SIGTRAN association can carry tens of thousands of MAP messages per second. Compliance: GSMA FS.07/FS.11 (/answers/gsma-fs07-fs11-signaling-firewall) apply to SIGTRAN exactly as they applied to classic SS7.

## Privacy and compliance considerations

SIGTRAN over the public internet without IPsec is a privacy risk — SS7 signalling contains IMSI, MSISDN, location, and routing data that should not be exposed. Modern operators wrap SIGTRAN in IPsec tunnels between peer STPs, or use private MPLS. Cross-border SIGTRAN traffic between operators is in scope for the data-export rules of both jurisdictions (EU GDPR Schrems II, KSA PDPL cross-border transfer rules). Mature operators document each SIGTRAN peer relationship and the legal basis for the data flow.

## Related

- [All answers](https://www.broadnet.me/answers)
- [Glossary](https://www.broadnet.me/answers)
- [How does SIGTRAN (SS7 over IP) work?](https://www.broadnet.me/answers/sigtran-explained)
- [SIGTRAN adaptation layers — M3UA, M2UA, SUA explained](https://www.broadnet.me/answers/sigtran-adaptation-layers)
- [What is SCTP (Stream Control Transmission Protocol)?](https://www.broadnet.me/answers/what-is-sctp)
- [SS7 MAP — what it is and why messaging still depends on it](https://www.broadnet.me/answers/ss7-map-explained)
- [GSMA FS.07 and FS.11 — the SS7 signalling firewall standards](https://www.broadnet.me/answers/gsma-fs07-fs11-signaling-firewall)
- [SS7 Firewall](https://www.broadnet.me/operators/ss7-firewall)
- [Signaling & CDR Intelligence](https://www.broadnet.me/platforms/signaling-cdr)