How to prevent LTE from searching infinitely for a connection when it cannot be found?

[newnow]

Dear Team,

I have a question regarding preventing LTE from endlessly searching for a network connection.
Lately I have been facing issues where LTE connection is rejected with EMM error 15. After it is rejected, LTE tries to find another connection and sometimes it takes several hours.

My question is: is there a configuration how to stop LTE search forever when there is no suitable connection - so that it doesn't block other modules from executing.

Thank you!

[Øyvind]

Hello, 

Do you use the Periodic cell search configuration %PERIODICSEARCHCONF? This is used to configure periodic cell searches in limited service state. Are you seeing the issue in an area with bad coverage? 

Kind regards,
Øyvind

[Achim Kraus]

Maybe you add the mfw version you use?

In my experience from the past you may be facing two issues (see %PERIODICSEARCHCONF - relation to EMM reject cause ).

While it may be clear for the modem firmware itself, if " EMM error 15" is treated as "sticky" or not, for the application it's not transparent. Depending on your M(V)NO, in my experience you may get such 15 (or other codes) also on short hiccups, but the modem will not retry that network for much longer until you "AT+CFUN=0/AT+CFUN=1". Very nasty because that may consume also more energy.

When the modem doesn't find a proper network, it may consider to stay idle for emergency calls. A very useful function for phones. Maybe not that valuable for an IoT device, where it drains the battery.

I wasn't able to find some statements about that in the change logs of the mfw (1.3.5 to 1.3.7), but an other ticket (see Potential bug entering PMS while searching network ) points into the direction, that there are changes. So, if you're not using a current mfw version, maybe you consider to check, if an update already helps.