Timer value
Default 60s (NOTE 2)
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
3GPP Scout / Reference / 5GS NAS timers / T3593
TS 24.501NAS timer
Timer T3593: 5GS session management, SMF side
In plain words
The SMF starts T3593 upon receiving PDU SESSION MODIFICATION COMPLETE for a command containing 5GSM cause #39 and performs network-requested PDU session release on expiry.
Our summary of the spec text quoted below.
What the spec says
Started when
Reception of PDU SESSION MODIFICATION COMPLETE message for transmitted PDU SESSION MODIFICATION COMMAND message where the PDU SESSION MODIFICATION COMMAND message included 5GSM cause #39
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
Stopped when
PDU SESSION RELEASE REQUEST message received
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
On expiry
Network-requested PDU session release procedure performed
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
State
PDU SESSION MODIFICATION PENDING
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
Note 2 of the table
NOTE 2: If the PDU Session Address Lifetime value is sent to the UE in the PDU SESSION MODIFICATION COMMAND message then timer T3593 shall be started with the same value, otherwise it shall use a default value.
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.2. © 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.