RUTC50 does not connect to LTE

[kbx]

RUTC50 does not connect to LTE

The attach procedure for this IMSI follows the standard attach message flow. The authentication occurs successfully, and the MME responds with the Attach Accept message. However, for unknown reason the eNB then sends a SACK message with an error indication of “unknown pair-ue-s1ap-id.​”

The MME UE S1AP ID communicated between from the MME to the eNB remains correct up until the initial context setup. For some reason the eNB is responding back to the MME with the message Unknown-pair-UE-S1AP-ID, which suggests that the UE is deciding to disconnect from the eNB due to a problem on the UE. The eNB is deleting the UE-S1AP-ID context and sending back to the MME Unknown-pair-UE-S1AP-ID.

Setting the APN/Band/Channel manually and turning off VoLTE does not help. SIM works in another brand modem

Latest firmware: RUTC_R_00.07.13.3

[Martynas]

Hello,

Thank you for reaching out. Could you please try the following steps to see if they resolve the issue?

1. Disable VoLTE via WebUI navigated to Network → Mobile → Connection (you can skip this step if it’s done already).
2. Execute the following command through the device CLI to disable IMS:

ubus -v call gsm.modem0 set_ims_state '{"state":"disabled","apply":true}'

Please let me know if this makes any difference or additional assistance is required.

Best regards,

[kbx]

Hi, I ran the command in the CLI but the modem still doesn’t connect. Is there anything else I can try?

Thanks

[Martynas]

Hi there @kbx,

In this case, to troubleshoot the issue more in-depth, we’ll need to contact you privately. A form for submission has been sent to your email inbox (used for registering on the forum). When completing it, please use 13017 as the ticket ID. Once submitted, we will reach out to you with further assistance.

Best regards,