MC7455 Won't connect to Network

IoT Modules MC/EM Series
1

SIM works on Android phone, but not on MC7455.

apn: fast.metropcs.com
name = MetroPCS US LTE
proxy = not set
port = not set
username = not set
password = not set
server = not set
mmsc = http://metropcs.mmsmvno.com/mms/wapenc
multimedia = not set
MCC = 310
MNC = 260
authentication type = not set
APN type = default,supl,mms
APN protocol = IPv6
APN roaming protocol = IPv4
bearer = unspecified
mobile virtual network operator type = GID
mobile virtual network operator value = 6D

Any ideas on how to get this connected?

at!gstatus?
!GSTATUS:
Current Time: 281 Temperature: 35
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Not attached
LTE band: B2 LTE bw: 10 MHz
LTE Rx chan: 1000 LTE Tx chan: 4294967295
LTE CA state: NOT ASSIGNED
EMM state: Deregistered Limited Service
RRC state: RRC Idle
IMS reg state: No Srv
PCC RxM RSSI: -68 RSRP (dBm): -101
PCC RxD RSSI: -70 RSRP (dBm): -101
Tx Power: – TAC: 0E00 (3584)
RSRQ (dB): -13.8 Cell ID: 00378618 (3638808)
SINR (dB): -1.2
OK

at!usbcomp?
Config Index: 1
Config Type: 1 (Generic)
Interface bitmask: 0000010D (diag,nmea,modem,rmnet0)
OK

at+cmee=1
OK

ati
Manufacturer: Sierra Wireless, Incorporated
Model: MC7455
Revision: SWI9X30C_02.33.03.00 r8209 CARMD-EV-FRMWR2 2019/08/28 20:59:30
MEID: 35907206649842
IMEI: 359072066498425
IMEI SV: 20
FSN: LQ950644740410
+GCAP: +CGSM
OK

at!priid?
PRI Part Number: 9909124
Revision: 001.000
Customer: Generic-M2M
Carrier PRI: 9999999_9904609_SWI9X30C_02.33.03.00_00_GENERIC_002.072_000
OK

at+cpin?
+CPIN: READY
OK

at+cimi
310260353730494
OK

at+cgdcont?
+CGDCONT: 1,“IPV4V6”,“fast.metropcs.com”,“0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0”,0,0,0,0
OK
at+cgpaddr=1

at!band?
Index, Name
00, All bands
OK

at+cops?
+COPS: 2
OK

at+cops=?
+cops: (0,“AT&T”,“AT&T”,“310410”,2),(0,“311 490”,“311 490”,“311490”,7),(0,“AT&T”,“AT&T”,“310410”,7),(0,“Verizon”,“Verizon”,“311480”,7),(0,“Sprint”,“Sprint”,“310120”,7),(0,“311 882”,“311 882”,“311882”,7),(0,“312 530”,“312 530”,“312530”,7),(0,“Metro by T-Mobile”,“Metro by”,“310260”,7),(0,“313 100”,“313 100”,“313100”,7),(0,“Metro by T-Mobile”,“Metro by”,“310260”,2),(0,1,2,3,4),(0,1,2)
OK

at+cops=1,2,“310260”,2
+CME ERROR: SIM failure

2

Hi @mindrcr,
Maybe you can share some below:

  • Had the module worked perfectly with the SIM before? If yes, did you take any new settings?
  • The module respones +CME ERROR: SIM failure. That would also explain why you were unable to register with the network. Have you tried to reset the module? Please do an AT!RESET and try again
  • Did you remove the SIM for a too short period of time then inserting it again? If yes, it might cause the issue. Reset module will resolve the problem

Please share any concerns you have. Help us tick Solution if your question is answered
Thanks

3

@mindrcr,

So you have the COPS mode set to 2 which is ‘deregister from the network’, I would suggest sending the below to the unit and letting it run to allow it to sort itself out.

at+cops=0
at+creg=1 ;These unsolicited responses will give you a running indication of attach status
at+cgreg=1
at+cereg=1
at!reset

The SIM failure can quite often indicate that the unit has been rejected from the network in its attach attempt.

Regards

Matt

4

The SIM works in an android phone. The SIM fits perfectly in the adapter with no edges causing issues. There are 3 drag marks across the SIM and adapter where the router is making contact. I have cleaned the SIM and tried inserting and restarting many times. Could it possibly be the SIM reader (hardware) issue? The only command that seems to fail is the at+cops commands.

at+cgatt=1
ERROR

at+ceer
+CEER: EMM attach failed

at+cops=0
+CME ERROR: SIM failure

at+creg=1
OK

at+cgreg=1
OK

at+cereg=1
OK

5

One further finding. The CNUM command is not bringing back the phone number. Will this cause an issue?
AT+CNUM
OK

6

I tried a TMobile SIM and changed only the APN setting, no other changes. It connected right away. Must be the missing MSISDN number not returned by CNUM. Thanks for the help.

7

I noticed that you were using IPV6 in your working Android example, but IPV4V6 with the MC7455. I believe this is more likely to cause issues if the APN only supports IPv6.

8

Was there ever a solution to this issue? I appear to also have an identical issue with a Google Fi (data or regular) SIM. I also have the data mode set to IPV6 only.

9

Turns out the issue in my case was somehow the IMEI on the (legit) Sierra modem was reset/wiped in a botched firmware upgrade. Resetting the IMEI fixed it (though I assume we’re not allowed to say how to reset the IMEI on this forum).