Hello,
We have devices with Quectel M66 GSM modems that were operating without issues for about 1 year. After this time they suddenly cannot re-register to network until SIM card is replaced. We are using SIM cards operated by 1NCE, which use roaming.
AT logs when problem occurs:
MODEM: powered on
MODEM: sending ATI (1/3)
--> ATI
<-- OK
MODEM: ATI ok
MODEM: enabling time sync
--> AT+CTZU=1
<-- OK
MODEM: enable time sync ok
MODEM: disabling command echo
--> ATE0
<-- OK
MODEM: disabling command echo ok
MODEM: getting IMEI
--> AT+GSN
<-- OK
MODEM: get IMEI ok
MODEM: IMEI = 869247049898536
MODEM: checking SIM PIN
--> AT+CPIN?
<-- +CPIN: READY
MODEM: SIM PIN ok
MODEM: configuring SMS
--> AT+CMGF=1
<-- OK
MODEM: configuring SMS ok
MODEM: getting CCID
--> AT+CCID
<-- OK
MODEM: get CCID ok
MODEM: CCID = 89882280666028794091
MODEM: setting register URC (2)
--> AT+CGREG=2
<-- OK
MODEM: set register URC ok
MODEM: waiting for network registration
--> AT+CGREG?
<-- +CGREG: 2,2
--> AT+CGREG?
<-- +CGREG: 2,2
--> AT+CGREG?
<-- +CGREG: 2,2
--> AT+CGREG?
<-- +CGREG: 2,2
--> AT+CGREG?
<-- +CGREG: 2,0
--> AT+CGREG?
<-- +CGREG: 2,0
--> AT+CGREG?
<-- +CGREG: 2,0
(this status is then repeated until timeout)
It looks like ME is stopping to search for new operator after a while.
After replacing SIM card in faulty device it register to network successfully:
MODEM: powered on
MODEM: sending ATI (1/3)
--> ATI
<-- OK
MODEM: ATI ok
MODEM: enabling time sync
--> AT+CTZU=1
<-- OK
MODEM: enable time sync ok
MODEM: disabling command echo
--> ATE0
<-- OK
MODEM: disabling command echo ok
MODEM: getting IMEI
--> AT+GSN
<-- OK
MODEM: get IMEI ok
MODEM: IMEI = 869247049898536
MODEM: checking SIM PIN
--> AT+CPIN?
<-- +CPIN: READY
MODEM: SIM PIN ok
MODEM: configuring SMS
--> AT+CMGF=1
<-- OK
MODEM: configuring SMS ok
MODEM: getting CCID
--> AT+CCID
<-- OK
MODEM: get CCID ok
MODEM: CCID = 89882280666023813474
MODEM: setting register URC (2)
--> AT+CGREG=2
<-- OK
MODEM: set register URC ok
MODEM: waiting for network registration
--> AT+CGREG?
<-- +CGREG: 2,2
(above command and response repeated until registered)
--> AT+CGREG?
<-- +CGREG: 2,5,"A036","AACB"
MODEM: registered
MODEM: roaming = 1
MODEM: LAC = A036, CID = AACB
MODEM: RAT = 1
There seems to be no issue with SIM card because problem does not occur after inserting “faulty” SIM card into another device of the same type. Suprisingly after inserting this card back to device which wasn’t working before, the device register successfully again.
Looks like ME is blocking this SIM card in some way until another SIM card is inserted.
Thank you for any suggestion in advance. I hope I have described my issue thoroughly.
Adam