Grey Route (SMS Grey Route)

Also known as: SMS Grey Route, Grey Routing

A grey route is an SMS delivery path that is technically functional but commercially or contractually unauthorised, typically an A2P (application-to-person) message injected into a P2P (person-to-person) interconnect to avoid the higher A2P termination fee. Grey routes deprive the destination operator of A2P revenue, evade content filtering and are a common carrier for spam, phishing and SMS pumping.

Categories: Roaming and InterconnectFraudInternet and Routing

Grey Route in context

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.

Telecom fraud costs operators an estimated $40+ billion per year. Common vectors include IRSF, Wangiri callback scams, SIM box bypass, PBX hacking and A2P grey routing.

To place Grey Route in the wider telecom-security picture, review BGCF, Refile, FASG, GSMA Permanent Reference Documents (IR Series), Spam and Toll Fraud — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.