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Popular Messages

NAS 5G

5G NAS - Registration Request

Starts a 5G registration or mobility update by sending UE identity and registration intent to the core.

UE -> AMF 3GPP TS 24.501
RRC 5G

5G NR - RRC Setup

Downlink NR RRC message sent by the gNB to establish SRB1 and move the UE into the connected RRC procedure.

gNB -> UE 3GPP TS 38.331
NGAP 5G

5G NR - Initial UE Message

NGAP initiating message used by the NG-RAN to transfer the UE's first uplink NAS message to the AMF.

NG-RAN -> AMF 3GPP TS 38.413
NAS LTE

LTE Attach Request

Attach Request is the EPS NAS message the UE uses to start the LTE attach procedure and ask the network to create EPS mobility-management context.

UE -> MME 3GPP TS 24.301
LTE RRC LTE

LTE RRC Connection Setup

Downlink LTE RRC message sent by the eNodeB to establish SRB1 and move the UE into connected-mode signaling.

eNodeB -> UE 3GPP TS 36.331
LTE RRC LTE

LTE RRC SIB1 - System Information Block Type 1

Broadcast LTE RRC message on BCCH and DL-SCH that gives the UE the essential access identity, cell selection, scheduling, and change-detection context needed before it can use the wider SIB set.

eNodeB -> UE 3GPP TS 36.331
NAS LTE

LTE Security Mode Command

Security Mode Command is the EPS NAS message the MME sends to activate the selected NAS security algorithms and move the LTE/EPS procedure into protected signaling.

MME -> UE 3GPP TS 24.301
RRC 5G

5G NR - RRC Setup Complete

Uplink NR RRC message sent by the UE on SRB1 and DCCH to confirm successful RRC connection establishment and transfer the initial NAS message.

UE -> gNB 3GPP TS 38.331
NAS LTE

LTE Authentication Request

Authentication Request is the EPS NAS message the MME uses to challenge the UE during EPS NAS authentication and verify the subscriber before later security and mobility procedures continue.

MME -> UE 3GPP TS 24.301
LTE RRC LTE

LTE RRC SIB2 - System Information Block Type 2

Broadcast LTE RRC system information block carried inside System Information that gives the UE the common radio, access barring, timer, and uplink-related context needed before normal LTE access can proceed.

eNodeB -> UE 3GPP TS 36.331
NAS LTE

LTE Service Request

Service Request is the EPS NAS message the UE uses to restore a NAS signaling connection and re-establish radio and S1 bearers while valid EPS context already exists.

UE -> MME 3GPP TS 24.301
RRC 5G

5G NR - RRC Setup Request

Uplink NR RRC message sent by the UE on SRB0 and CCCH to request establishment of an RRC connection.

UE -> gNB 3GPP TS 38.331
LTE RRC LTE

LTE RRC SIB4 - System Information Block Type 4

Broadcast LTE RRC system information block carried inside System Information that provides intra-frequency neighbor-cell detail used during idle-mode camping and same-frequency cell reselection.

eNodeB -> UE 3GPP TS 36.331
NAS LTE

LTE Tracking Area Update Request

Tracking Area Update Request is the EPS NAS message the UE uses to update the network about tracking-area change, periodic presence, or related EPS mobility-context refresh.

UE -> MME 3GPP TS 24.301
NAS 5G

5G NAS - PDU Session Release Request

PDU Session Release Request is the 5GSM message the UE sends when it wants to end an already active PDU session, or when it needs to release the session because of a local protocol or service condition.

UE -> SMF via AMF 3GPP TS 24.501
RRC 5G

5G NR - RRC Reconfiguration

Reconfigures the UE radio connection after setup, including bearers, measurements, and mobility.

gNB -> UE 3GPP TS 38.331
RRC 5G

5G NR - System Information Block 1 (SIB1)

SystemInformationBlockType1 (SIB1) is the key NR broadcast system information block that tells the UE how to access the cell, select PLMN context, and interpret important cell-level access restrictions and configuration.

gNB -> UE 3GPP TS 38.331
RRC 5G

5G NR - System Information Block 5 (SIB5)

System Information Block 5 (SIB5) is an NR broadcast system information block used for inter-RAT mobility context, helping the UE evaluate reselection toward other radio access technologies such as LTE.

gNB -> UE 3GPP TS 38.331
RRC 5G

5G NR - System Information Block 8 (SIB8)

System Information Block 8 (SIB8) is an NR broadcast system information block used for inter-RAT mobility context toward cdma2000 systems where that legacy mobility path still exists.

gNB -> UE 3GPP TS 38.331
NAS LTE

LTE Attach Accept

Attach Accept is the EPS NAS message the MME uses to grant LTE attach and deliver the accepted EPS mobility context to the UE.

MME -> UE 3GPP TS 24.301
NAS LTE

LTE Attach Complete

Attach Complete is the EPS NAS message the UE sends after Attach Accept to confirm that the granted attach context was received and processed.

UE -> MME 3GPP TS 24.301
NAS LTE

LTE Authentication Response

Authentication Response is the EPS NAS message the UE sends after Authentication Request to return the calculated response parameter and let EPS authentication continue.

UE -> MME 3GPP TS 24.301
LTE RRC LTE

LTE RRC SIB3 - System Information Block Type 3

Broadcast LTE RRC system information block carried inside System Information that gives the UE the serving-frequency cell reselection rules used in idle mode after the common SIB1 and SIB2 context is already known.

eNodeB -> UE 3GPP TS 36.331
NAS LTE

LTE Tracking Area Update Accept

Tracking Area Update Accept is the EPS NAS message the MME uses to accept the tracking area updating procedure and return the updated EPS mobility context to the UE.

MME -> UE 3GPP TS 24.301