Name in the cause table
ngKSI already in use
Source: 3GPP TS 24.501 V20.1.0, clause 9.11.3.2, table 9.11.3.2.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
3GPP Scout / Reference / 5GMM causes / 5GMM cause #71
TS 24.5015GMM cause
5GMM cause #71: ngKSI already in use
In plain words
The UE sends this cause to the network in N1 mode when the ngKSI in an AUTHENTICATION REQUEST is already associated with a stored 5G security context.
Our summary of the spec text quoted below.
What the spec says
When it is used
This 5GMM cause is sent to the network in N1 mode if the ngKSI value received in the AUTHENTICATION REQUEST message is already associated with one of the 5G security contexts stored in the UE.
Source: 3GPP TS 24.501 V20.1.0, clause A.3. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
How this page was made
3GPP Scout built this page from TS 24.501 V20.1.0 as indexed on 2026-10-15. The quotes are copied from the spec, and code checks each one against the stored text and the 3GPP archive file before publishing. The plain-words line was written by an AI model (GPT-6 Sol) and checked against the quotes by a second AI model from another company (Claude Opus 5.5). The official 3GPP text governs.