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Error codes › EMM cause (LTE NAS)

EMM cause #9 UE identity cannot be derived by the network

EMM cause (LTE NAS)3GPP TS 24.301 §9.9.3.9 and Annex A

What it means

UE identity cannot be derived by the network: the MME couldn't map the GUTI the phone used to an IMSI (e.g. the old MME is unreachable). The phone normally re-attaches with its IMSI.

Where you see it

In LTE NAS Attach reject, Tracking area update reject, Service reject or Detach request.

What to check

Usually self-healing; if repeated, check the MME-to-MME (S10) context fetch.

Look at the S6a (MME↔HSS) and S11 messages just before the reject: they usually show the real trigger.

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Related codes

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