CLI Refile / A-Number Manipulation

Also known as: A-Number Manipulation

CLI refile is an interconnect-level fraud where a transit carrier rewrites the Calling Line Identification (A-number) on international calls to disguise their true origin and evade termination charges, quality metrics or lawful-interception targeting. It is closely related to grey-route SMS refile and typically detected by A-number/routing correlation analytics.

Categories: Radio Access NetworkRoaming and InterconnectThreats and Attacks

CLI Refile 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.

Roaming and interconnect are where two operators exchange signaling and user-plane traffic. Trust boundaries here are the primary attack surface for location tracking, SMS interception and fraud, which is why GSMA now mandates SEPP with PRINS on 5G interconnect.

To place CLI Refile in the wider telecom-security picture, review IRSF, Toll Bypass, Wangiri Fraud, Refile Fraud, SIMBox Fraud and ISUP: each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

Related topic hubs

  • Roaming Security IPX/GRX interconnect risk, home-routed vs local-breakout, SEPP.
  • Diameter Attacks S6a IDR/PUR/CLR abuse, subscriber tracking, LTE signaling attacks.
  • SMS Firewall SMS spam, phishing, A2P bypass and MAP-layer SMS filtering.
  • Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.

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