EM7455 can't connect to T-Mobile (+CME ERROR: no network service)

I have a rebranded (Dell) EM7455 that works great on AT&T but I can’t get it to connect to T-Mobile. When I try AT!SCACT=1,1 it returns +CME ERROR: no network service

I know my SIM is active because I can put it in a microtik router and everything works fine.

What I have tried:

1a. Flashing the modem with the Generic firmware package:

sudo qmi-firmware-update -t /dev/ttyUSB0 --update-qdl SWI9X30C_02.33.03.00.cwe SWI9X30C_02.33.03.00_GENERIC_002.072_000.nvu
sudo qmi-firmware-update -t /dev/ttyUSB0 --update-qdl SWI9X30C_02.33.03.00.cwe SWI9X30C_02.33.03.00_GENERIC_002.072_000.nvu

1b. AT command results:

at!entercnd="A710"
OK
at!priid="9904609","002.072","GENERIC"
OK
at!priid?
PRI Part Number: 9904609
Revision: 002.072
Customer: GENERIC

Carrier PRI: 9999999_9904609_SWI9X30C_02.33.03.00_00_GENERIC_002.072_000
Carrier PRI: 9999999_9904594_SWI9X30C_02.32.11.00_00_ATT_002.070_002
Carrier PRI: 9999999_9904780_SWI9X30C_02.33.03.00_00_VERIZON_002.079_001

OK
at!gobiimpref?
!GOBIIMPREF:
preferred fw version:    02.33.03.00
preferred carrier name:  GENERIC
preferred config name:   GENERIC_002.072_000
preferred subpri index:  000
current fw version:      02.33.03.00
current carrier name:    GENERIC
current config name:     GENERIC_002.072_000
current subpri index:    000

OK
at!gstatus?
!GSTATUS:
Current Time:  168              Temperature: 27
Reset Counter: 12               Mode:        ONLINE         
System mode:   LTE              PS state:    Attached     
LTE band:      B4               LTE bw:      20 MHz  
LTE Rx chan:   2300             LTE Tx chan: 20300
LTE CA state:  NOT ASSIGNED
EMM state:     Registered       Normal Service
RRC state:     RRC Idle       
IMS reg state: No Srv   

PCC RxM RSSI:  -88              RSRP (dBm):  -118
PCC RxD RSSI:  -89              RSRP (dBm):  -122
Tx Power:      --               TAC:         352C (13612)
RSRQ (dB):     -10.6            Cell ID:     01713302 (24195842)
SINR (dB):      6.6


OK
at+creg?
+CREG: 0,1

OK
+CGREG: 0,1

OK
at+cereg?
+CEREG: 0,1

OK
at!scact=1,1
+CME ERROR: no network service

2a. Flashing the modem with the TMO (Generic) firmware package:

sudo qmicli -d /dev/cdc-wdm0 -p --dms-set-firmware-preference="02.30.01.01,002.045_001,GENERIC"
sudo qmi-firmware-update -t /dev/ttyUSB0 --update-qdl SWI9X30C_02.30.01.01.cwe SWI9X30C_02.30.01.01_GENERIC_002.045_001.nvu

This particular package didn’t bring up /dev/ttyUSB2 until I did the following command as well

sudo qmicli -d /dev/cdc-wdm0 -p --dms-swi-set-usb-composition=6

2b. AT command results:

at!entercnd="A710"
OK
at!priid="9904609","002.045","GENERIC"
OK
at!gstatus?
!GSTATUS:
Current Time:  1052             Temperature: 26
Reset Counter: 11               Mode:        ONLINE         
System mode:   LTE              PS state:    Attached     
LTE band:      B4               LTE bw:      20 MHz  
LTE Rx chan:   2300             LTE Tx chan: 20300
LTE CA state:  NOT ASSIGNED
EMM state:     Registered       Normal Service
RRC state:     RRC Idle       
IMS reg state: No Srv   

PCC RxM RSSI:  -87              RSRP (dBm):  -120
PCC RxD RSSI:  -90              RSRP (dBm):  -123
Tx Power:      --               TAC:         352C (13612)
RSRQ (dB):     -12.9            Cell ID:     01713302 (24195842)
SINR (dB):      4.0


OK
at!impref?
!IMPREF:
preferred fw version:    02.30.01.01
preferred carrier name:  GENERIC
preferred config name:   GENERIC_002.045_001
current fw version:      02.30.01.01
current carrier name:    GENERIC
current config name:     GENERIC_002.045_001

OK

at+creg?
+CREG: 0,1

OK
at+cgreg?
+CGREG: 0,1

OK
at+cereg?
+CEREG: 0,1

OK

at+cops?
+cops: 0,0,"T-Mobile",7

OK

at!scact=1,1
+CME ERROR: no network service

Any ideas? My modem with an AT&T SIM card works great (using the ATT package).

I tried on a non-rebranded EM7455 from Digikey, same issue.

Hi @ww1 ,

The log shows the module is able to attach T-Mobile network successfully. Data connection just is activated when the module should be set APN corresponds to TMobile’s. Please share the response of PDP context configuration by the command below
AT+CGDCONT?
Thanks

2 Likes

Thanks for getting back to me so quickly!

I thought it might be an APN issue, I tried “fast.t-mobile.com” with IP, IPV4V6, and IPV6 for good measure. I also tried “epc.t-mobile.com

at+cgdcont?
+CGDCONT: 1,"IPV4V6","fast.t-mobile.com","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0

OK

I will call T-mobile today and see if it is a problem on their end, but it sounds like there aren’t any red flags from the modem itself which is good to hear.

Called tech support. The T-Mobile “unlimited data” plans are cell phone only and can’t be used with WWAN modems

Tried 3 different plans, none of them worked. I wonder if T-Mobile just has the EM7455 blacklisted or something. I’ll post if I actually get it working, but at this point I might just stick with AT&T.