Timer value
NOTE 8
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.1. © 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 / T3587
TS 24.501NAS timer
Timer T3587: 5GS session management, UE side
In plain words
The UE starts T3587 on MBS join rejection with back-off for sessions not started or not starting soon and requests joining on expiry if needed.
Our summary of the spec text quoted below.
What the spec says
Started when
PDU SESSION MODIFICATION COMMAND message or PDU SESSION ESTABLISHMENT ACCEPT message received with Received MBS information that includes MBS decision set to "MBS join is rejected" and Rejection cause set to "multicast MBS session has not started or will not start soon" and an MBS back-off timer value
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
Stopped when
None
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
On expiry
Initiating a request to join the multicast MBS session associated with the PDU session if still needed
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
State
PDU SESSION ACTIVE
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24501-k10.zip in the 3GPP archive.
Note 8 of the table
NOTE 8: The value of this timer is provided by the network in the Received MBS container IE (see clause 6.3.2.3, clause 6.4.1.3 and clause 9.11.4.31).
Source: 3GPP TS 24.501 V20.1.0, clause 10.3, table 10.3.1. © 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.