A1 Interface (Non-RT RIC to Near-RT RIC Interface)

Also known as: A1, A1-P, A1-EI, A1-ML

The A1 interface is the O-RAN control-plane interface from the Non-RT RIC (in the SMO) down to the Near-RT RIC. It carries three service categories: A1-P (policy) to guide xApp behaviour, A1-EI (enrichment information) to feed contextual data to xApps, and A1-ML (ML model management) for model lifecycle. Compromise of A1 lets an attacker push arbitrary policies and models into the live RAN.

Categories: Radio Access Network

A1 Interface 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.

To place A1 Interface in the wider telecom-security picture, review 1G, 2G, 5G, 5G SA, 5G NSA and 5GNR — 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.