3GPP Scout / Reference / 5GS NAS timers / T3516

TS 24.501NAS timer

Timer T3516: 5GS mobility management, UE side

TS 24.501 V20.1.0Clause 10.2Table 10.2.1Checked 2026-10-15

In plain words

The UE starts T3516 when RAND and RES* are stored after a 5G authentication challenge and deletes them on expiry.

Our summary of the spec text quoted below.

What the spec says

Timer value

30s NOTE 7 NOTE 8 In WB-N1/CE mode, 48s For access via a satellite NG-RAN cell, 35s NOTE 12

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

Started when

RAND and RES* stored as a result of an 5G authentication challenge

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

Stopped when

SECURITY MODE COMMAND message received SERVICE REJECT message received REGISTRATION ACCEPT message received AUTHENTICATION REJECT message received AUTHENTICATION FAILURE message sent 5GMM-DEREGISTERED, 5GMM-NULL or 5GMM-IDLE mode entered

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

On expiry

Delete the stored RAND and RES*

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

State

5GMM-REGISTERED-INITIATED 5GMM-REGISTERED 5GMM-DEREGISTERED-INITIATED 5GMM-SERVICE-REQUEST-INITIATED

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

Same timer in EPS (TS 24.301)

TS 24.301 defines the corresponding timer for EPS. Its page quotes the EPS wording.

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.