RM502Q-AE - Telkomsel IMS VOLTE & 5G NSA issue

IoT Modules 5G Module
1

Hi team,

Sent an email to support but will write here since it is a personal use.

Currently, I’m not able to attach 5G NSA & IMS with Telkomsel (51010)

Is there custom configuration/firmware needed or how to check it is a hardware issue (antenna/etc?)

We can confirm 5G NSA is enabled on location (new Huawei Lampsite installed) and IMSI is allowed for 5G.
For IMS, it is confirmed that IMSI is allowed too (tested on Android/iOS)

RM502QAEAAR13A04M4G_01.200.01.200

AT+COPS=?
+COPS: (1,“Tsel-MelayaniSepenuhHati”,“Telkomse”,“51010”,7),(1,“IND INDOSAT”,“INDOSAT”,“51001”,7),(1,“Smartfren”,“SF”,“51009”,7),(1,“3”,“3”,“51089”,7),(1,“IND XL”,“XL”,“51011”,7),(0-4),(0-2)

AT+COPS?
+COPS: 0,0,“Tsel-MelayaniSepenuhHati”,7

AT+QENG=“servingcell”
+QENG: “servingcell”,“NOCONN”,“LTE”,“FDD”,510,10,208270B,414,1850,3,5,5,4DA,-77,-11,-46,16,13,70,-

+QNWPREFCFG: “mode_pref”,LTE:NR5G
+QNWPREFCFG: “nr5g_disable_mode”,0
+QCAINFO: “PCC”,1850,100,“LTE BAND 3”,1,414,-76,-10,-43,9
+QCAINFO: “SCC”,38750,100,“LTE BAND 40”,1,414,-84,-8,-66,0,0,-,-

For IMS

AT+QCFG=“ims”
+QCFG: “ims”,1,0

AT+CGDCONT?
+CGDCONT: 1,“IPV4V6”,“internet”,“0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0”,0,0,0,0,“”,0
+CGDCONT: 2,“IPV4V6”,“ims”,“0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0”,0,0,0,0,“”,0
+CGDCONT: 3,“IPV4V6”,“sos”,“0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0”,0,0,0,1,“”,0

AT+CGPADDR
+CGPADDR: 1,“10.65.117.156,36.4.0.192.38.35.101.48.24.136.86.254.105.194.125.46”
+CGPADDR: 2,“36.4.0.192.36.58.2.107.24.136.86.254.137.19.91.88”
+CGPADDR: 3,“”

Many thanks!

2

hi team, any assistance?

3

Hi,

The problem is mainly caused by Telkomsel. However, this is not a technical fault, but a deliberate network policy.

At Telkomsel, IMEI and device whitelisting is applied. Only certified smartphones (Android and iOS) are allowed to trigger 5G NSA (EN-DC). Data modems, such as the RM502, are intentionally not supported in most locations.

As a result, LTE works very well and LTE carrier aggregation is active, but the 5G NR connection never attaches. This behavior is due to Telkomsel’s network policy, not a modem malfunction.

IMS service is also restricted. It only works with approved device profiles and known SIP User-Agent configurations. Although the RM502 technically supports IMS, its IMS REGISTER request is rejected by Telkomsel’s IMS core network.

Therefore, even if the IMSI is allowed, the device itself is not authorized.

This is clearly not a hardware or antenna issue. Signal levels are strong, LTE CA is stable, and the RF performance is normal.

4

Hi @Emre_Karabek,

AT+QENDC
+QENDC: 1,1,0,1,0

based on 5G_Network_Application docs, it is not restricted. do you have any ideas why?

Screenshot 2026-01-09 at 21.02.39
Screenshot 2026-01-09 at 21.02.391812×786 53.4 KB

5

After further investigation, it is possible to attach 5G NSA with firmware “RM502QAEAAR11A04M4G_01.004.01.004”

it is not working with firmware “RM502QAEAAR11A04M4G_01.203.01.203”

AT+QENG=“servingcell”
+QENG: “servingcell”,“NOCONN”
+QENG: “LTE”,“FDD”,510,10,207EE21,320,500,1,5,5,4DA,-105,-13,-72,12,0,-,22
+QENG: “NR5G-NSA”,510,10,65535,-32768,-32768,-32768

AT+CREG?
+CREG: 2,1,“04DA”,“207EE21”,7

AT+CEREG?
+CEREG: 2,1,“04DA”,“207EE21”,7

AT+QCAINFO
+QCAINFO: “PCC”,500,100,“LTE BAND 1”,1,320,-107,-16,-71,0

need further help to debug this issue

1 Like
6

Dear @morpig
RM520QEA is data-only, so it doesn’t support IMS.
For NSA, did you test there firmware version? Only RM502QAEAAR11A04M4G_01.004.01.004 worked, right?
All things are the same, right? Like SIM card, antenna and others.

7

The fields shown in the documents are general information at the RRC/PLMN level published to the UE.
Does the current cell support EN-DC?
1 = Supports
This information only indicates that the base station is technically capable of EN-DC.
This does not mean that the relevant UE can connect to EN-DC.
Does the registered PLMN support EN-DC?
1 = Supports
This indicates that Telkomsel’s 5G NSA infrastructure is available.
However, it does not mean that the UE is authorized on this PLMN.

The debug outputs shared later reveal the problem more clearly.

Two different firmware versions appear.
In one version, the EN-DC procedure is initiated and Secondary gNB is added.
In this case, the NR signal values ​​being -32768 is normal in Huawei Lampsite scenarios.
In the other firmware version, NR is not visible at all.
This indicates that the EN-DC procedure was never triggered.

This situation means: The network is authorized for EN-DC, SIM/IMSI is authorized, RF conditions are met, but the modem is not initiating the EN-DC request or the gNB is not accepting this request.

In conclusion, Telkomsel does not appear to have any problems on the SIM and RF sides.