Connectivity Issues with New SIM

We continue to have issues with the SIMs that are preventing trial deployment and providing significant frustration. We activated a new SIM to place into our product, but what we are seeing are intermediate connectivity issues. With the new SIM, output of the AT+CSQ command repeated every second will return 99,99 for a long period of time and then 29,99 for just a few seconds before returning to 99,99. We are unable to establish a connection and the output of the AT+CEREG is not showing that we have registered.

In contrast the older registered SIM placed in the same hardware always shows the signal strength of 29,99 and can connect immediately.

Before suggesting to use a cellphone, the whole point of our current exercise is to be able to have our devices register automatically as soon as they have power. Suggestions would be appreciated as would explanation of what we should be seeing with a SIM when placed into the device.



Hey Jason,

Can you please email with your SIM number so we can look into it. Also adding your device’s make and model could be helpful.

As far as the cellphone option, the reason why we recommend that step is because we have seen several hardware manufacturers not provide their modem the required amount of time to fully scan the network. On first use network registration can take longer than usual so having the full scan time is important. Cellphone manufacturers tend to be the most reliable when it comes to giving modems the scan time they need.


We had been doing the scan manually so we could set the time ourselves. Your comment about scan time led us down a path looking into how long we were scanning for each network type and we discovered that the Quectel BG96 that we use will spend a significant time scanning for NBIoT coverage. We changed our output to show which network we were scanning for and determined that we are better off timing out the scanning on our own. Doing so let us register after a few attempts. Hopefully this helps someone else.



Thanks for the followup longtimer!

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