Modem quectel RM502Q-AE is stuck showing LIMSRV and cannot detect 4g

Stevedan · January 4, 2024, 5:56pm

We are using the quectel modem RM502Q with our product, but we encontered an issue when running this modem in Equador. Although this does not happen in Spain. What is strange is the fact that when we used it 2 months ago, everything was able to connect. All of a sudden, last month it stop connecting to any newtork provider in Equador and we were not able to detect 4g but 3g. With 3g we were not able to connect because we keep seeing limited service.
After looking at the servingcell, we get the following error->

sudo mmcli -m 0 -- command='AT+QENG="servingcell"'
response: '+QENG: "servingcell","LIMSRV","WCDMA",740,02,9D08,29A840,662,180,200,-53,-2,-,-,-,-,-'.

In addition to that we are not able to detect any 4g service, even though using the phone we get this service.

jfrog · January 4, 2024, 6:19pm

According to this page your operator 740 02 CNT Mobile uses 1700 MHz band (B4) that should be supported by RM50xQ-AE. I suggest checking with another modem or a phone what is really available at the given location.

Stevedan · January 4, 2024, 7:26pm

We checked with a phone and get the following

Stevedan · January 4, 2024, 7:28pm

The strange this is that we observe this behavior both in other provider at that area. CNT/Movistart and claro. FOr more information

sudo mmcli -m 0 --command='AT+QMBNCFG="list"'
response: '+QMBNCFG: "List",0,1,1,"ROW_Commercial",0x0A010809,202101151
+QMBNCFG: "List",1,0,0,"FirstNet",0x0A015300,202101151
+QMBNCFG: "List",2,0,0,"5G-ATT",0x0A015700,202101151
+QMBNCFG: "List",3,0,0,"ROW_Generic_3GPP_PTCRB_GCF",0x0A01FB09,202102071
+QMBNCFG: "List",4,0,0,"Rogers_Canada",0x0A014800,202101151
+QMBNCFG: "List",5,0,0,"Bell_Canada",0x0A014700,202101151
+QMBNCFG: "List",6,0,0,"Telus_DataOnly",0x0A014900,202101151
+QMBNCFG: "List",7,0,0,"Commercial-Sprint",0x0A010204,202101151
+QMBNCFG: "List",8,0,0,"Commercial-TMO",0x0A01050F,202101151
+QMBNCFG: "List",9,0,0,"VoLTE-ATT",0x0A010335,202101151
+QMBNCFG: "List",10,0,0,"CDMAless-Verizon",0x0A010126,202101151
+QMBNCFG: "List",11,0,0,"Telia_Sweden",0x0A012400,202101151
+QMBNCFG: "List",12,0,0,"TIM_Italy_Commercial",0x0A012B00,202101151
+QMBNCFG: "List",13,0,0,"France-Commercial-Orange",0x0A010B21,202101151
+QMBNCFG: "List",14,0,0,"Commercial-DT-VOLTE",0x0A011F1F,202101151
+QMBNCFG: "List",15,0,0,"Germany-VoLTE-Vodafone",0x0A010449,202101151
+QMBNCFG: "List",16,0,0,"UK-VoLTE-Vodafone",0x0A010426,202101151
+QMBNCFG: "List",17,0,0,"Commercial-EE",0x0A01220B,202101151
+QMBNCFG: "List",18,0,0,"Optus_Australia_Commercial",0x0A014400,202101151
+QMBNCFG: "List",19,0,0,"Telstra_Australia_Commercial",0x0A010F00,202101151
+QMBNCFG: "List",20,0,0,"Commercial-LGU",0x0A012608,202101151
+QMBNCFG: "List",21,0,0,"Commercial-KT",0x0A01280B,202101151
+QMBNCFG: "List",22,0,0,"Commercial-SKT",0x0A01270A,202101151
+QMBNCFG: "List",23,0,0,"Commercial-Reliance",0x0A011B0C,202101151
+QMBNCFG: "List",24,0,0,"Commercial-SBM",0x0A011C0B,202101151
+QMBNCFG: "List",25,0,0,"Commercial-KDDI",0x0A010709,202101151
+QMBNCFG: "List",26,0,0,"Commercial-DCM",0x0A010D0D,202101151
+QMBNCFG: "List",27,0,0,"VoLTE-CU",0x0A011561,202101151
+QMBNCFG: "List",28,0,0,"VoLTE_OPNMKT_CT",0x0A0113E0,202101151
+QMBNCFG: "List",29,0,0,"Volte_OpenMkt-Commercial-CMCC",0x0A012010,202101151'

jfrog · January 4, 2024, 7:44pm

I would disable MBN

AT+QMBNCFG="AutoSel",0
AT+QMBNCFG="Deactivate"
AT+CFUN=1,1

Stevedan · January 4, 2024, 8:03pm

Out of curiosity, the modem carrier should not be ROW right?
We use modem manager and we get the carrier ROW_COMERCIAL also. It should find a specific carrier right?, could that be the problem? Is there a reason why it doesnt detect the carrier?


    General  |                    path: /org/freedesktop/ModemManager1/Modem/0
           |               device id: 57923ab712413b96221fb779c07028cd873676fb
  -----------------------------------
  Hardware |            manufacturer: Quectel
           |                   model: RM500Q-AE
           |       firmware revision: RM500QAEAAR11A02M4G
           |          carrier config: ROW_Commercial
           | carrier config revision: 0A010809
           |            h/w revision: 20000
           |               supported: gsm-umts, lte, 5gnr
           |                 current: gsm-umts, lte, 5gnr
           |            equipment id: 867197050463971
  -----------------------------------
  System   |                  device: /sys/devices/pci0000:00/0000:00:15.0/usb1/1-8
           |                 drivers: option, qmi_wwan
           |                  plugin: quectel
           |            primary port: cdc-wdm0
           |                   ports: cdc-wdm0 (qmi), ttyUSB0 (qcdm), ttyUSB1 (gps),
           |                          ttyUSB2 (at), ttyUSB3 (at), wwan0 (net)
  -----------------------------------
  Numbers  |                     own: 593996184243
  -----------------------------------
  Status   |                    lock: sim-pin2
           |          unlock retries: sim-pin (3), sim-puk (10), sim-pin2 (3), sim-puk2 (10)
           |                   state: searching
           |             power state: on
           |          signal quality: 100% (cached)

jfrog · January 4, 2024, 8:09pm

You don’t really need MM to check the registration, you only need a dumb terminal like minicom or picocom.
My recommendation was to not use a Carrier Config at all.

Stevedan · January 5, 2024, 7:11pm

Still does not detect it the 4g.

                                            <<<<<< QMUX:
                                            <<<<<<   length  = 136
                                            <<<<<<   flags   = 0x80
                                            <<<<<<   service = "nas"
                                            <<<<<<   client  = 4
                                            <<<<<< QMI:
                                            <<<<<<   flags       = "response"
                                            <<<<<<   transaction = 117
                                            <<<<<<   tlv_length  = 124
                                            <<<<<<   message     = "Get System Info" (0x004D)
                                            <<<<<< TLV:
                                            <<<<<<   type       = "Result" (0x02)
                                            <<<<<<   length     = 4
                                            <<<<<<   value      = 00:00:00:00
                                            <<<<<<   translated = SUCCESS
                                            <<<<<< TLV:
                                            <<<<<<   type       = "WCDMA Service Status" (0x13)
                                            <<<<<<   length     = 3
                                            <<<<<<   value      = 01:01:00
                                            <<<<<<   translated = [ service_status = 'limited' true_service_status = 'limited' preferred_data_path = 'no' ]
                                            <<<<<< TLV:
                                            <<<<<<   type       = "LTE Service Status" (0x14)
                                            <<<<<<   length     = 3
                                            <<<<<<   value      = 00:00:00
                                            <<<<<<   translated = [ service_status = 'none' true_service_status = 'none' preferred_data_path = 'no' ]
                                            <<<<<< TLV:
                                            <<<<<<   type       = "WCDMA System Info v2" (0x18)
                                            <<<<<<   length     = 33
                                            <<<<<<   value      = 01:00:01:03:01:01:01:00:01:08:9D:01:40:A8:29:00:00:00:00:01:37:34:30:30:32:FF:01:00:01:03:01:B4:00
                                            <<<<<<   translated = [ domain_valid = 'yes' domain = 'none' service_capability_valid = 'yes' service_capability = 'cs-ps' roaming_status_valid = 'yes' roaming_status = 'on' forbidden_valid = 'yes' forbidden = 'no' lac_valid = 'yes' lac = '40200' cid_valid = 'yes' cid = '2730048' registration_reject_info_valid = 'no' registration_reject_domain = 'none' registration_reject_cause = 'none' network_id_valid = 'yes' mcc = '740' mnc = '02' hs_call_status_valid = 'yes' hs_call_status = 'hsdpa-hsupa-unsupported' hs_service_valid = 'yes' hs_service = 'hsdpa-hsupa-supported' primary_scrambling_code_valid = 'yes' primary_scrambling_code = '180' ]
                                            <<<<<< TLV:
                                            <<<<<<   type       = "Additional WCDMA System Info" (0x1d)
                                            <<<<<<   length     = 6
                                            <<<<<<   value      = FF:FF:02:00:00:00
                                            <<<<<<   translated = [ geo_system_index = '65535' cell_broadcast_support = 'on' ]
                                            <<<<<< TLV:
                                            <<<<<<   type       = "WCDMA Call Barring Status" (0x20)
                                            <<<<<<   length     = 8
                                            <<<<<<   value      = 03:00:00:00:03:00:00:00
                                            <<<<<<   translated = [ cs_status = 'all-calls' ps_status = 'all-calls' ]
                                            <<<<<< TLV:
                                            <<<<<<   type       = "WCDMA Cipher Domain" (0x23)
                                            <<<<<<   length     = 1
                                            <<<<<<   value      = 00
                                            <<<<<<   translated = none
                                            <<<<<< TLV:
                                            <<<<<<   type       = "SIM Reject Info" (0x27)
                                            <<<<<<   length     = 4
                                            <<<<<<   value      = 04:00:00:00
                                            <<<<<<   translated = cs-ps-invalid
                                            <<<<<< TLV:
                                            <<<<<<   type   = 0x28
                                            <<<<<<   length = 1
                                            <<<<<<   value  = 03
                                            <<<<<< TLV:
                                            <<<<<<   type       = "WCDMA Routing Area Code" (0x2d)
                                            <<<<<<   length     = 1
                                            <<<<<<   value      = C8
                                            <<<<<<   translated = 200
                                            <<<<<< TLV:
                                            <<<<<<   type       = "Network Selection Registration Restriction" (0x2f)
                                            <<<<<<   length     = 4
                                            <<<<<<   value      = 00:00:00:00
                                            <<<<<<   translated = unrestricted
                                            <<<<<< TLV:
                                            <<<<<<   type   = 0x32
                                            <<<<<<   length = 4
                                            <<<<<<   value  = 00:00:00:00
                                            <<<<<< TLV:
                                            <<<<<<   type       = "NR5G Service Status Info" (0x4a)
                                            <<<<<<   length     = 3
                                            <<<<<<   value      = 00:00:0