One Plus UE not attaching to the Network

[SiddharthGoyal17]

Hi,

I am using srsRAN with USRP X310 and 5GOS, following this tutorial https://docs.srsran.com/projects/project/en/latest/tutorials/source/cotsUE/source/index.html#configuration.

I can successfully establish a connection between RU and core network but One Plus Ue is not getting attached.

Setup Details

1. Device Name: One Plus 10 Pro 5G
2. Model: NE2213
3. SIM Card: sysmoUSIM-SJS1
4. Core Network: Open 5GS
5. Using SA Network and Preferred network type: 5G/4G/3G/2G (Auto) selected

Behaviour:

1. With the above setup I am able to attach following UEs: Motorola Edge 30 Pro, Google Pixel 6 and Asus Zenfone 9, however not able to attach One Plus UE. "INFO: InitialUEMessage" print is not observed in amf logs.

2. However, when VoLTE is turned ON there is an InitialUEMessage seen in the logs and the UE attaches to the network and also goes online for 30 seconds. For approximately 40 seconds there is a data connectivity also. and then it drops out of network.
   In the scenario i am running VoLTE need to be disabled.

Any suggestions or guidance on the above issue would be really helpful!!

AMF Logs with VoLTE off:
01/20 15:11:04.968: [amf] INFO: [Added] Number of gNBs is now 1 (../src/amf/context.c:1277)
01/20 15:11:04.968: [amf] INFO: gNB-N2[127.0.0.1] max_num_of_ostreams : 30 (../src/amf/amf-sm.c:941)
01/20 15:11:38.777: [amf] INFO: gNB-N2[127.0.0.1] connection refused!!! (../src/amf/amf-sm.c:954)
01/20 15:11:38.777: [amf] INFO: [Removed] Number of gNBs is now 0 (../src/amf/context.c:1305)
01/20 15:11:58.216: [amf] INFO: gNB-N2 accepted[127.0.0.1]:37271 in ng-path module (../src/amf/ngap-sctp.c:113)
01/20 15:11:58.216: [amf] INFO: gNB-N2 accepted[127.0.0.1] in master_sm module (../src/amf/amf-sm.c:894)
01/20 15:11:58.225: [amf] INFO: [Added] Number of gNBs is now 1 (../src/amf/context.c:1277)
01/20 15:11:58.226: [amf] INFO: gNB-N2[127.0.0.1] max_num_of_ostreams : 30 (../src/amf/amf-sm.c:941)
01/20 15:12:24.277: [amf] INFO: gNB-N2[127.0.0.1] connection refused!!! (../src/amf/amf-sm.c:954)
01/20 15:12:24.277: [amf] INFO: [Removed] Number of gNBs is now 0 (../src/amf/context.c:1305)
01/20 15:16:04.761: [amf] INFO: gNB-N2 accepted[127.0.0.1]:37558 in ng-path module (../src/amf/ngap-sctp.c:113)
01/20 15:16:04.761: [amf] INFO: gNB-N2 accepted[127.0.0.1] in master_sm module (../src/amf/amf-sm.c:894)
01/20 15:16:04.769: [amf] INFO: [Added] Number of gNBs is now 1 (../src/amf/context.c:1277)
01/20 15:16:04.769: [amf] INFO: gNB-N2[127.0.0.1] max_num_of_ostreams : 30 (../src/amf/amf-sm.c:941)

Amf Logs with VolTE switched ON:
01/20 15:11:58.225: [amf] INFO: [Added] Number of gNBs is now 1 (../src/amf/context.c:1277)
01/20 15:11:58.226: [amf] INFO: gNB-N2[127.0.0.1] max_num_of_ostreams : 30 (../src/amf/amf-sm.c:941)
01/20 15:12:24.277: [amf] INFO: gNB-N2[127.0.0.1] connection refused!!! (../src/amf/amf-sm.c:954)
01/20 15:12:24.277: [amf] INFO: [Removed] Number of gNBs is now 0 (../src/amf/context.c:1305)
01/20 15:16:04.761: [amf] INFO: gNB-N2 accepted[127.0.0.1]:37558 in ng-path module (../src/amf/ngap-sctp.c:113)
01/20 15:16:04.761: [amf] INFO: gNB-N2 accepted[127.0.0.1] in master_sm module (../src/amf/amf-sm.c:894)
01/20 15:16:04.769: [amf] INFO: [Added] Number of gNBs is now 1 (../src/amf/context.c:1277)
01/20 15:16:04.769: [amf] INFO: gNB-N2[127.0.0.1] max_num_of_ostreams : 30 (../src/amf/amf-sm.c:941)
01/20 15:17:02.326: [amf] INFO: gNB-N2[127.0.0.1] connection refused!!! (../src/amf/amf-sm.c:954)
01/20 15:17:02.326: [amf] INFO: [Removed] Number of gNBs is now 0 (../src/amf/context.c:1305)
01/20 15:19:52.568: [amf] INFO: gNB-N2 accepted[127.0.0.1]:49119 in ng-path module (../src/amf/ngap-sctp.c:113)
01/20 15:19:52.568: [amf] INFO: gNB-N2 accepted[127.0.0.1] in master_sm module (../src/amf/amf-sm.c:894)
01/20 15:19:52.577: [amf] INFO: [Added] Number of gNBs is now 1 (../src/amf/context.c:1277)
01/20 15:19:52.578: [amf] INFO: gNB-N2[127.0.0.1] max_num_of_ostreams : 30 (../src/amf/amf-sm.c:941)
01/20 15:20:38.086: [gmm] WARNING: [imsi-001010000009936] Mobile Reachable Timer Expired (../src/amf/gmm-sm.c:791)
01/20 15:20:38.215: [amf] INFO: InitialUEMessage (../src/amf/ngap-handler.c:437)
01/20 15:20:38.215: [amf] INFO: [Added] Number of gNB-UEs is now 1 (../src/amf/context.c:2789)
01/20 15:20:38.215: [amf] INFO: RAN_UE_NGAP_ID[0] AMF_UE_NGAP_ID[24] TAC[7] CellID[0x66c000] (../src/amf/ngap-handler.c:598)
01/20 15:20:38.215: [amf] INFO: [suci-0-001-01-0-0-0-0000009936] Known UE by 5G-S_TMSI[AMF_ID:0x20040,M_TMSI:0xc0000475] (../src/amf/context.c:1920)
01/20 15:20:38.215: [gmm] INFO: Registration request (../src/amf/gmm-sm.c:1339)
01/20 15:20:38.215: [gmm] INFO: [suci-0-001-01-0-0-0-0000009936] 5G-S_GUTI[AMF_ID:0x20040,M_TMSI:0xc0000475] (../src/amf/gmm-handler.c:196)
01/20 15:20:38.215: [gmm] INFO: [suci-0-001-01-0-0-0-0000009936] 5G-S_GUTI[PLMN_ID:0xf110,AMF_ID:0x20040,M_TMSI:0xc0000475] (../src/amf/gmm-handler.c:609)
01/20 15:20:38.405: [gmm] INFO: [imsi-001010000009936] Registration complete (../src/amf/gmm-sm.c:2698)
01/20 15:20:38.405: [amf] INFO: [imsi-001010000009936] Configuration update command (../src/amf/nas-path.c:609)
01/20 15:20:38.405: [gmm] INFO: UTC [2026-01-20T14:20:38] Timezone[0]/DST[0] (../src/amf/gmm-build.c:551)
01/20 15:20:38.405: [gmm] INFO: LOCAL [2026-01-20T15:20:38] Timezone[3600]/DST[0] (../src/amf/gmm-build.c:556)
01/20 15:20:38.405: [gmm] WARNING: [imsi-001010000009936] Ue requested DNN "ims" Not Supported OR Not Subscribed in the Slice (../src/amf/gmm-handler.c:1370)
01/20 15:20:38.555: [gmm] INFO: UE SUPI[imsi-001010000009936] DNN[internet] S_NSSAI[SST:1 SD:0xffffff] smContextRef[37] smContextResourceURI[http://127.0.0.4:7777/nsmf-pdusession/v1/sm-contexts/37] (../src/amf/gmm-handler.c:1383)
01/20 15:20:38.562: [amf] WARNING: [imsi-001010000009936:2] Receive Update SM context(DUPLICATED_PDU_SESSION_ID) (../src/amf/nsmf-handler.c:689)
01/20 15:20:38.562: [amf] INFO: [imsi-001010000009936:2:19][0:0:NULL] /nsmf-pdusession/v1/sm-contexts/{smContextRef}/modify (../src/amf/nsmf-handler.c:947)
01/20 15:20:38.570: [amf] WARNING: UnRef NF EndPoint(addr) [127.0.0.4:7777] (../src/amf/nsmf-handler.c:144)
01/20 15:20:38.570: [amf] INFO: Setup NF EndPoint(addr) [127.0.0.4:7777] (../src/amf/nsmf-handler.c:144)
01/20 15:20:38.638: [amf] INFO: [imsi-001010000009936:2:11][0:0:NULL] /nsmf-pdusession/v1/sm-contexts/{smContextRef}/modify (../src/amf/nsmf-handler.c:947)
01/20 15:20:54.355: [gmm] WARNING: [imsi-001010000009936] Ue requested DNN "ims" Not Supported OR Not Subscribed in the Slice (../src/amf/gmm-handler.c:1370)
01/20 15:21:10.375: [gmm] WARNING: [imsi-001010000009936] Ue requested DNN "ims" Not Supported OR Not Subscribed in the Slice (../src/amf/gmm-handler.c:1370)
01/20 15:21:18.946: [amf] INFO: [imsi-001010000009936:2:13][0:0:NULL] /nsmf-pdusession/v1/sm-contexts/{smContextRef}/modify (../src/amf/nsmf-handler.c:947)
01/20 15:21:19.086: [amf] INFO: UE Context Release [Action:2] (../src/amf/ngap-handler.c:1733)
01/20 15:21:19.086: [amf] INFO: RAN_UE_NGAP_ID[0] AMF_UE_NGAP_ID[24] (../src/amf/ngap-handler.c:1734)
01/20 15:21:19.086: [amf] INFO: SUCI[suci-0-001-01-0-0-0-0000009936] (../src/amf/ngap-handler.c:1738)
01/20 15:21:19.086: [amf] INFO: [Removed] Number of gNB-UEs is now 0 (../src/amf/context.c:2796)
01/20 15:21:39.162: [amf] WARNING: UnRef NF EndPoint(addr) [127.0.0.4:7777] (../src/amf/namf-handler.c:268)
01/20 15:21:39.162: [amf] INFO: Setup NF EndPoint(addr) [127.0.0.4:7777] (../src/amf/namf-handler.c:268)
01/20 15:21:45.168: [gmm] WARNING: [imsi-001010000009936] Paging failed. Stop (../src/amf/gmm-sm.c:700)

Logs:
I am attaching ngap.pcap logs with VolTE enabled.

Thanks and Regards,
Siddharth Goyal

gnb_ngap_with_volte.zip