ATSSS (Access Traffic Steering, Switching and Splitting)

Also known as: Access Traffic Steering Switching Splitting

ATSSS is the 3GPP Release 16 feature that lets a UE simultaneously use 3GPP and non-3GPP accesses (for example 5G NR and Wi-Fi) for a single PDU session, with the network steering, switching or splitting flows based on policy. It uses MP-TCP and MP-QUIC proxies at the UPF and dedicated PCF policy control, and underpins tightly integrated Wi-Fi and 5G convergence.

Categories: Identity and SubscriberProtocols and StandardsInternet and Routing

ATSSS in context

Subscriber identifiers (IMSI, SUPI, MSISDN, IMEI) anchor authentication, charging and lawful interception. Any protocol that leaks a permanent identifier is treated as a privacy defect, which is why 5G introduced SUCI concealment on the air interface.

Telecom security is written into standards from 3GPP, GSMA, ETSI, IETF and ITU-T. Understanding which body owns which specification, and how they interlock, is essential for both design and audit work.

To place ATSSS in the wider telecom-security picture, review 3G, 3GPP, ADSL, A5/1, BGP and CGNAT — 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.