# What is TCAP?

> TCAP (Transaction Capabilities Application Part) is the SS7 layer that manages request/response dialogues between network nodes, carrying application operations such as MAP on top of SCCP. Every HLR query and MT-ForwardSM that delivers an SMS is a TCAP transaction. Because TCAP wraps the MAP operations attackers abuse, it is a key inspection point for SS7 signaling firewalls. See /answers/what-is-sccp, /answers/ss7-map-explained, and /operators/ss7-firewall.

- Canonical URL: https://www.broadnet.me/answers/what-is-tcap
- Language: en
- Last reviewed: 2026-07-22
- Publisher: BroadNet (https://www.broadnet.me)

## Related

- [All answers](https://www.broadnet.me/answers)
- [Glossary](https://www.broadnet.me/answers)
- [What is SCCP?](https://www.broadnet.me/answers/what-is-sccp)
- [OCS, IN, and INAP — operator real-time charging explained](https://www.broadnet.me/answers/ocs-in-inap-explained)
- [SS7 MAP — what it is and why messaging still depends on it](https://www.broadnet.me/answers/ss7-map-explained)
- [What is SS7?](https://www.broadnet.me/answers/what-is-ss7)
- [SIGTRAN — SS7 over IP explained](https://www.broadnet.me/answers/what-is-sigtran)
- [SS7 Firewall](https://www.broadnet.me/operators/ss7-firewall)
- [Signaling & CDR Intelligence](https://www.broadnet.me/platforms/signaling-cdr)