Hey > I hope someone can help shed some light onto this issue as I am at a loss. > > I am investigating an issue that is occurring in a few IoT devices where > either the modem has trouble registering to the network or it is being > rejected shortly after a data connection is established. I'm trying to get a > better understanding of the error messages reported in the modem manager logs. > > In the case where the modem is not able to register to the network, the logs > will show: > > <warn> [modem25] network reject indication received > <warn> [modem25] service domain: cs-ps > <warn> [modem25] radio interface: lte > <warn> [modem25] reject cause: no-suitable-cells-in-location-area > <warn> [modem25] network reject indication received > <warn> [modem25] service domain: cs-ps > <warn> [modem25] radio interface: lte > <warn> [modem25] reject cause: plmn-not-allowed > > My first thought was that the sim card was not properly provisioned, however > deactivated sims show a different error message. I've contacted my service > provider for some insight, but they don't see any network issues on their > end: neither with the cell equipment or my sim cards. > > The odd thing is that after some time, the device is able to register to the > network and will then easily connect before being rejected again, this time > with the following error message: > > <warn> [modem2] network reject indication received > <warn> [modem2] service domain: ps > <warn> [modem2] radio interface: lte > <warn> [modem2] reject cause: implicitly-detached > > I'm interested in what the reject causes above may mean as that might provide > some insight on possible fixes on the device side of the connection. > > I am using the Telit LE910C4 modem with modem manager 1.18.8 in tandem with > network manager. The modem is mounted within a custom made IoT device. >
Not exactly sure what leads to these problems, but something you can check is whether the operator you're using expects to use a specific set of APN settings **during network attach**. In LTE, the network registration flow involves agreeing on APN settings to use, to establish the initial default EPS bearer. You can see the current configured settings in the "mmcli -m a" output in the 3GPP section. If the section is empty, you don't have explicit settings (and you may need them). Changing these settings can be done with mmcli, e.g.: $ mmcli -m a --3gpp-set-initial-eps-bearer-settings="apn=internet,ip-type=ipv4v6" See https://modemmanager.org/docs/modemmanager/ip-connectivity-setup-in-lte-modems/ for some context -- Aleksander
