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Cinterion connection reliability

ivan141

April 9, 2014 - 3:30pm, 5194 views

I am currently involved in the creation of an alert notification system that uses cinterion mc55i based modems (siemens TC35i and a newer cinterion that is also mc55i based).

Have noticed some strange behaviours happening on site at our client, and I'm hoping someone can maybe explain what is happening.

First thing I noticed is that the modems are losing their GSM network registration (CREG=0,2 or 0,3 instead of 0,1) after periods of inactivity. The thing that worries me is that the modem is not able to recover from this without a software reset (CFUN,1,1). We suspect the provider has some sort of rule in place bouncing inactive connections from it's network, but it's difficult to find someone who will be able to confirm or deny this at the provider.

Second thing is that I sometimes run into something that looks like memory issues, where the modem is no longer able to send SMS messages, when this happens I see that it still responds to received messages, but their contents are garbled or empty. Managed to recover from this state manually by triggering a wipe of all memory, but it should not be possible for memory to run out because we only send with CGMS, and delete all incoming messages immediately after reading them.

Any help on any of the 2 mentioned issues would be most welcome because this issue is a potentially blocking issue for the further commissioning of our project.

Thanks in advance!

Regards,
Ivan