LTE: Attach Reject

If the UE initiated ATTACH REQUEST cannot be accepted by the network, the MME shall send an ATTACH REJECT message to the UE including an appropriate EMM cause value

If the attach procedure fails due to a Default EPS bearer Setup Failure or an ESM procedure failure or operator determined barring is applied on Default EPS Bearer Context Activation during attach procedure, the MME shall combine the ATTACH REJECT message with a PDN CONNECTIVITY REJECT message contained in the ESM Message Container IE. In this case the EMM Cause value in the ATTACH REJECT message shall be set to #19 "ESM failure"

If the attach request is rejected due to NAS level congestion control, the network shall set the EMM cause value to #22 "congestion" and optionally assigns a back-off timer T3346

Reference: 3GPP TS 24.301

Example: ATTACH REJECT Message


  1. HI,

    can you please explain what is ESM failure means?

  2. nice sun glasses!

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  3. So in which RRC msg this attach req will be embedded and sent again after the back off time?
    Should rrc stay in connected mode after getting attach reject?

  4. What will UE do after getting attach reject?