O-RAN Interfaces (A1, E2, O1, O2)

O-RAN Interfaces (A1, E2, O1, O2) in context

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

Signaling protocols carry the control-plane instructions that set up calls, register subscribers, hand over sessions 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 FS.11 / FS.19 / FS.20 as a top-tier telecom risk.

To place O-RAN Interfaces (A1, E2, O1, O2) in the wider telecom-security picture, review Revenue Assurance, O1 Interface, Diameter, Interconnect Security Model, Man-in-the-Middle (MITM) and SC.

Related terms

• Revenue Assurance
• O1 Interface
• Diameter
• Interconnect Security Model
• Man-in-the-Middle (MITM)
• SC
• 5G Reference Points
• F1 Interface

Equipment

O-RAN units and RIC (O-RU, O-DU, O-CU, RIC, SMO)

• A1 Interface
• Cloud RAN
• E2 Interface
• Fronthaul
• Midhaul
• Near-RT RIC
• Non-RT RIC
• O-Cloud
• O-CU
• O-DU
• All 21 terms

Articles in the P1 mobile network security guide

Related topic hubs

• Open RAN Security O-RAN xApp/rApp, E2/A1/O1 interfaces and RIC security.
• SS7 Security SS7/MAP/CAP/SCCP attacks and defenses across 2G/3G interconnect.
• Diameter Attacks S6a IDR/PUR/CLR abuse, subscriber tracking, LTE signaling attacks.
• Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.

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.