PSTN (Public Switched Telephone Network)

The Public Switched Telephone Network is the global circuit-switched telephone network that originated in the 19th century with analog exchanges and is now a mixture of TDM and IP-based replacements. PSTN is being progressively retired in favour of all-IP VoLTE, VoNR, and SIP interconnect, but legacy SS7 ISUP signalling and copper-pair access remain in service in many markets.

Categories: Radio Access NetworkSignalingRoaming and Interconnect

PSTN in context

The radio access network is where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations and downgrade attacks; defenses rest on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

Signaling protocols carry the control-plane messages that set up calls, register subscribers and route SMS. SS7, Diameter, GTP-C and SIP are the four dominant families, and interconnect exposure of any of them is treated by GSMA as top-tier telecom risk.

To place PSTN in the wider telecom-security picture, review Certification Authority (CA), Firewall, IBCF, Interconnect Security Model, Inter-PLMN Security and mTLS — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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