Hi experts!
I’m trying to connect an EG91 module using an AT&T SIM, but I cannot success, it only gives me CREG: 0,0, and occasionally CREG: 0,4.
This is the general sequence I’m using:
ATE0
QICSGP
GSN
CPIN
CREG [Cannot pass here due to answer]
QUIDEACT
QIACT
QIACT?
I’m in Mexico.
I was wondering if you could help me to identify the problem.
Hi Eliacim,
Thank you for the question. It seems your EG91 module isn’t able to register on the network with an AT&T SIM in Mexico. The responses +CREG: 0,0 (not registered, not searching) and +CREG: 0,4 (unknown) indicate the module cannot camp on a cell. Network registration must succeed before you can activate PDP context (AT+QIACT).
Try these steps:
AT+CFUN?
Should return +CFUN: 1. If not, run AT+CFUN=1.
AT+CPIN?
Should return +CPIN: READY. Enter PIN if required.
AT+CSQ
Low or 99 = no usable signal.
AT+COPS=0
AT+QCFG=“roamservice”,2
AT+QICSGP=1,1,“broadband”,“”,“”,1
AT+QIACT=1
AT+QIACT?
Think of registration like passing “border control”: if it fails, data activation won’t work.
If it still fails, please share outputs of:
AT+CFUN?
AT+CSQ
AT+COPS?
AT+QCFG=“roamservice”
This will help identify why the module cannot register.
Have a great day!
Best Regards,
Ananthan
Hi!
I still cannot register.
Here I show results:
AT+CFUN?
+CFUN: 1
AT+CSQ
+CSQ: 99,99
AT+COPS?
+COPS: 0
AT+QCFG:“roamservice”
+QCFG: “roamservice,2” OK
Yesterday I got the register only 1 time, connected as a roaming service, but just one time, the rest of intents I got the same issue: 0,0 or 0,4.
Thnks!
I wait for your answer.
Hello, you have: +CSQ: 99,99. This can mean several things: either an antenna problem, a network registration issue (IP/APN), or a problem with the LTE-M mode selection. You absolutely must have this initially: AT+COPS=1,2,“+operator” and then:
AT+CGDCONT=1,“+your APN”
Hi Eliacim,
Thanks for the update. The results you shared point to a signal (RF) issue.
The key output is:
AT+CSQ
+CSQ: 99,99
99,99 means the module cannot detect any cellular signal. Without signal, the module cannot register on the network, which explains the CREG: 0,0 and CREG: 0,4 results.
Your other settings look correct:
CFUN: 1 → RF is enabled
COPS: 0 → Automatic network selection
Roaming is enabled
Since the module registered once before, the SIM and configuration are likely OK. This strongly suggests a hardware or environment issue.
Please check the following:
-Ensure the cellular antenna is properly connected (reseat it if needed).
-Try a different known-good antenna, if possible.
-Test in a location with good cellular coverage (near a window or outdoors).
Also check Band / RAT configuration:
If bands or RATs were previously restricted, registration may fail.
AT+QCFG=“nwscanmode”,0,1
AT+QCFG=“band”
Make sure the module is allowed to scan all supported RATs and bands used by roaming networks in Mexico.
For additional diagnostics, you may also run:
AT+QCSQ
AT+QENG=“servingcell”
For testing, you may also try using a local SIM card (non-roaming) to verify whether this is a hardware-related issue.
Have a great day!
Best Regards,
Ananthan