3GPP Scout / Reference / EPS NAS timers / T3440
TS 24.301NAS timer
In plain words
The UE starts T3440, for example, on receiving ATTACH REJECT, DETACH REQUEST or TRACKING AREA UPDATE REJECT with a listed EMM cause. The UE releases the NAS signalling connection when T3440 expires in the listed cases.
Our summary of the spec text quoted below.
10s NOTE 7 (applicable to case k) in clause 5.3.1.2.1) NOTE 8 In WB-S1/CE mode, 34s (applicable to case k) in clause 5.3.1.2.1) NOTE 14 NOTE 15 NOTE 16 NOTE 17
Source: 3GPP TS 24.301 V20.1.0, clause 10.2, table 10.2.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24301-k10.zip in the 3GPP archive.
ATTACH REJECT, DETACH REQUEST, TRACKING AREA UPDATE REJECT with any of the EMM cause #3, #6, #7, #8, #11, #12, #13, #14, #15, #22, #25, #31, #35, #36, #42 or #78 SERVICE REJECT received with any of the EMM cause #3, #6, #7, #8, #11, #12, #13, #15, #22, #25 [...]
Source: 3GPP TS 24.301 V20.1.0, clause 10.2, table 10.2.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24301-k10.zip in the 3GPP archive.
NAS signalling connection released Bearers have been set up or a request for PDN connection for emergency bearer services or a CS emergency call is started Upon receipt of ESM DATA TRANSPORT message as described in clause 5.3.1.2.1 (NOTE 9)
Source: 3GPP TS 24.301 V20.1.0, clause 10.2, table 10.2.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24301-k10.zip in the 3GPP archive.
Release the NAS signalling connection for the cases a), a1), b), b1), c), d), e), f), g), h), i), j), k), l), m) and n) as described in clause [...]
Source: 3GPP TS 24.301 V20.1.0, clause 10.2, table 10.2.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24301-k10.zip in the 3GPP archive.
Table 10.2.1 has 1 more row for T3440 that cover other cases. Read it in the official text.
TS 24.501 defines the corresponding timer for 5GS. Its page quotes the 5GS wording.
3GPP Scout built this page from TS 24.301 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.