GL7600 getting intermittent +CMS ERROR: 287 error

I’m trying to use GL7600 to send SMS, but I’m getting very strange behavior. Sometimes it can work, sometimes it can’t work - I’m getting an +CMS Error: 287. This happens to the same 4G SIM card and modem unit.

Has anyone encountered something similar? Is there an AT command to verify if the unit is connected properly to the 4G network?

AT+CSQ doesn’t seem to work as a reliable indicator that the module is connected to the network.

Thanks in advance. :smiley:

OK
at+csq
+CSQ: 14,2

OK
at+cmgf=1
OK
at+cmgs="90123456"
> test
+CMS ERROR: 287
at
OK
at+cmgs="90123456"
> test
+CMS ERROR: 38
at+cmgs="90123456"
> test
+CMS ERROR: 38
at+csq
+CSQ: 99,99

OK
at+csq
+CSQ: 99,99

OK
at+csq
+CSQ: 7,2

OK
at+cmgf=1
OK
at+cmgs="90123456"
> test
+CMGS: 20

OK

Hello,
As per logs we can also see +CMS ERROR: 38 which means “Network out of order”.

You can set RAT of the module using AT+KSRAT command and check if module registers on network or not by using command AT+CREG.

for more details on these commands refer to AT Command guide at this link https://source.sierrawireless.com/resources/airprime/software/airprime_hl76xx_at_commands_interface_guide/

Thanks & Regards,
Rex

Thanks Rex! I also noticed that the modem LED indicator light has to blink before it is really connected.

This problem still exists and is very inconsistent. Sometimes, my GL7600 can connect to 4G network, sometimes it can’t. However, if I use the SIM card on my iPhone 6s, I’m always able to connect to the 4G network. I need to repeatedly turn on and off power to the terminal until it can successfully connect - I know this when the LED light blinks.

I’m not sure what’s the problem. Is it a firmware or hardware bug or an antenna problem?

Will appreciate any help!