5GS MM Cause #62: No Network Slices Available — NSSAI Rejection Diagnosis

5GS MM cause #62 (“No network slices available”) is the most common cause code encountered during 5G network slicing field tests. It appears in a Registration Reject message when the AMF (Access and Mobility Management Function) cannot grant any of the S-NSSAIs (Slice/Service Type + Slice Differentiator) included in the UE’s Requested NSSAI.

Understanding cause #62 is fundamental for validating private 5G deployments, enterprise network slicing rollouts, and any 5G SA field campaign where slice selection must be verified at the NAS layer.

Technical Reference

Network Slicing: What the NAS Exchange Looks Like

In a 5G SA registration with network slicing, the UE includes a Requested NSSAI IE in the Registration Request. Each entry is an S-NSSAI composed of:

• SST (Slice/Service Type, 1 byte): standardized values include eMBB (0x01), URLLC (0x02), MIoT (0x03), V2X (0x04)
• SD (Slice Differentiator, 3 bytes, optional): operator-specific value distinguishing multiple slices of the same SST

When the AMF receives the Registration Request, it validates each requested S-NSSAI against:

1. The UE’s subscription in the UDM (User Data Management)
2. The configured slices available in the current AMF and TA
3. The roaming agreements if the UE is a visitor

If none of the requested S-NSSAIs can be granted, the AMF returns a Registration Reject with cause #62.

UE Behavior After Receiving Cause #62

Per 3GPP TS 24.501 §5.5.1.2.5:

• Set 5GS update status to 5U3 ROAMING NOT ALLOWED
• Store all S-NSSAIs from the Requested NSSAI in the “Rejected NSSAI in the current PLMN” list — the UE shall not request these slices again in this PLMN
• Enter state 5GMM-DEREGISTERED
• If other configured S-NSSAIs exist that are not in the rejected list: the UE may initiate a new Registration Request with those slices
• If all S-NSSAIs are rejected: the UE enters 5GMM-DEREGISTERED.NO-SUPI or 5GMM-DEREGISTERED.PLMN-SEARCH depending on implementation

The Registration Reject may optionally include:

• Allowed NSSAI: what slices the AMF can offer (may differ from what was requested)
• Rejected NSSAI: a per-S-NSSAI cause code explaining why each slice was rejected (individual rejection causes per TS 24.501 §9.11.3.46)

Field Scenarios

Subscription not provisioned for the requested slice. The UDM does not include the requested S-NSSAI in the UE’s Subscribed S-NSSAIs. This is the most common cause during private 5G validation: the enterprise SIM is not yet provisioned with the correct slice identifiers. The AMF queries the UDM, finds no matching subscription, and rejects with cause #62.

Requested slice not deployed in this AMF or TA. The UE requests an S-NSSAI that exists in the operator’s network but has not been configured in the AMF serving this cell, or is not available in the current Tracking Area. Common during phased 5G SA slicing rollouts where the AMF slice configuration lags behind radio deployment.

Visited PLMN does not support the home PLMN’s slices. In roaming with network slicing, the visited PLMN must map the home S-NSSAIs to its own NSSAI (H-NSSAI to V-NSSAI mapping). If no mapping is configured for the requested slices, the visited AMF rejects with cause #62.

Test S-NSSAI mismatch. During 5G SA lab or trial deployments, the S-NSSAI values configured in the UE (via SIM or device settings) may not match those configured in the AMF. Even a 1-bit mismatch in the SST or SD produces a full rejection — cause #62 with no partial grant.

Step-by-Step Field Diagnosis

Step 1 — Decode the Registration Request. In the 5GS NAS log, locate the Registration Request and expand the Requested NSSAI IE. List all S-NSSAIs (SST + SD values) the UE attempted to request.

Step 2 — Confirm cause #62 in the Registration Reject. The 5GMM cause IE value should be 0x3E. Check whether the Registration Reject includes a Rejected NSSAI IE (type 0x11): this IE contains per-S-NSSAI rejection cause codes that provide more granular information than cause #62 alone.

Step 3 — Read the per-S-NSSAI rejection cause codes. Each entry in the Rejected NSSAI IE carries an individual rejection cause. Key values include: cause 0x01 (S-NSSAI not available in the current PLMN), cause 0x02 (S-NSSAI not available in the current registration area), cause 0x04 (S-NSSAI not available due to the maximum number of UEs reached), per TS 24.501 §9.11.3.46.

Step 4 — Compare with the UDM subscription. Verify that the UE’s IMSI/SUPI in the UDM contains the requested S-NSSAI in the Subscribed S-NSSAIs list. A missing or mismatched S-NSSAI at UDM level is the root cause in most provisioning-related rejections.

Step 5 — Verify the AMF’s configured NSSAI. On the AMF side, confirm the slice is configured in the AMF’s Network Slice Selection Policy (NSSP) and that the AMF supports the requested SST/SD combination for the current TA.

Capturing Cause #62 in the Field

5GS NAS Registration Reject messages are captured via DIAG log code 0xB821 (NR5G NAS OTA) or the NAS OTA packet log stream. The decoded Registration Reject shows the 5GMM cause IE value 0x3E labeled “No network slices available,” the full Requested NSSAI from the preceding Registration Request, and — when present — the per-S-NSSAI rejection causes in the Rejected NSSAI IE.

Correlate the Registration Reject timestamp with the SS-RSRP/SINR measurements at the same moment to confirm the rejection is NAS-origin and not triggered by a radio layer failure masquerading as a registration failure.

Related Cause Codes

• Cause #62 in LTE NAS — There is no direct equivalent in EPS NAS (TS 24.301). Network slicing is a 5G feature.
• Cause #67 — Insufficient resources for specific slice and DNN (PDU Session level, not registration level)
• Cause #72 — DNN not supported or not subscribed in the slice (PDU Session rejection after successful slice registration)
• Cause #73 — Insufficient resources for specific slice (slice-level resource exhaustion, no DNN specificity)
• Cause #43 — N1 mode not allowed (5G NAS mode itself is not authorized for this USIM)