3GPP Scout / Reference / 5GS NAS timers / Timers T3555 and T3570

TS 24.501NAS timer

Timers T3555 and T3570: Retransmission by the AMF

TS 24.501 V20.1.0Clause 10.2Table 10.2.2Checked 2026-10-15

Covers

TS 24.501 words these values in parallel, so they share this page. Each has its own section with the spec text and a plain explanation.

Timer T3555: 5GS mobility management, AMF side

5GS mobility management, AMF sideTable 10.2.2

In plain words

The AMF starts T3555 when sending CONFIGURATION UPDATE COMMAND with acknowledgement requested and retransmits the message when the timer expires.

Our summary of the spec text quoted below.

Timer value

6s In WB-N1/CE mode, 24s For access via a satellite NG-RAN cell, 11s NOTE 12

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

Started when

Transmission of CONFIGURATION UPDATE COMMAND message with "acknowledgement requested" set in the Acknowledgement bit of the Configuration update indication IE

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

On expiry

Retransmission of CONFIGURATION UPDATE COMMAND message

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

Stopped when

CONFIGURATION UPDATE COMPLETE message received

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

State

5GMM-REGISTERED

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

Timer T3570: 5GS mobility management, AMF side

5GS mobility management, AMF sideTable 10.2.2

In plain words

The AMF starts T3570 when sending IDENTITY REQUEST and retransmits the message when the timer expires.

Our summary of the spec text quoted below.

Timer value

6s In WB-N1/CE mode, 24s For access via a satellite NG-RAN cell, 11s NOTE 12

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

Started when

Transmission of IDENTITY REQUEST message

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

On expiry

Retransmission of IDENTITY REQUEST message

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

Stopped when

IDENTITY RESPONSE message received

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.

State

5GMM-COMMON-PROCEDURE-INITIATED

Source: 3GPP TS 24.501 V20.1.0, clause 10.2, table 10.2.2. © 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 lines were 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.