A Network List is a group of selected networks that has been selected from the Network Marketplace that the SIM is allowed to register on.
How does it work?
All Onomondo SIMs are "non-steering" SIMs. This allows the device to try and connect to any network with strong enough coverage instead of being "steered" by predefined list set on the list. When the device tries to connect to a local network, the local network will forward the request to Onomondo, as long as Onomondo has a commercial agreement with the local operator in place.
If a device requests access to a network that is not included in the Network List, our Core Network will notify the RAN that the device is not allowed to use the specific network. The local network will in turn inform the device that the network hasn't been enabled for the device. In this case, the module will respond with 0,3 while querying the network registration status (the command depends on the cellular technology).
AT+CREG?
+CREG: 0,3
AT+CGREG?
+CGREG: 0,3
AT+CEREG?
+CEREG: 0,3
In the Onomondo App. you will see the network rejection in the Network Logs. The event will be reported as "Not allowed to use data on network (...) reason: network_whitelist"
If the first local operator was rejected, the device will try to register with the next available network in the area. In line with cellular standards, the device will also add the rejected one to the Forbidden Network (FPLMN) list. This list is stored on the SIM, but it is managed by the device.
When the device requests access to a local network that is on the Network List, our Core confirms the request from the local RAN and the device can successfully authenticate with it. Once the device is authenticated, it registers on the network and the subscriber profile will be stored within its memory. In this case, the module will respond with 0,5 while querying the network registration status (the command depends on the cellular technology).
AT+CREG?
+CREG: 0,5
AT+CGREG?
+CGREG: 0,5
AT+CEREG?
+CEREG: 0,5
In the Onomondo App. you will see the network authentication and registration in the Network Logs. The events will be reported as "Allowed to use (...)" and "Attached (...) connection", respectively.
How often does the local network require authentication?
When a device is continuously connecting to the same part of the local network, it will not require to be authenticated again. It is only during the authentication process that the network can be blocked for not being on the Network List assigned to a SIM.
Otherwise, the local network uses the authentication stored in its memory during the registration process.
When does the device need to re-authenticate with a network?
There are three main scenarios where a local network will request authentication:
Device connecting to a new local network.
Device connecting to a new part of the same network.
After the authentication information is removed from the local network.
This can either happen from the local network due to inactivity, after a device actively detaches, or by our Core Network notifying the RAN (fx. if the SIM has been deactivated).
The Forbidden Network (FPLMN) List
Why does the device add the network to the FPLMN list when it is not allowed to connect to a network?
The FPLMN list is part of the cellular standards and is used so the device can reduce the number of networks it will try connecting to when it is looking to connect to a new network. This speeds up subsequent connection attempts by ignoring available networks that are forbidden.
Where can I find the FPLMN list?
The device will write the network to a FPLMN list on the SIM. Most devices keep a cached version in memory as well.
Suspect there is an issue with the FPLMN list on the device?
There are different ways to clear the FPLMN list once a network is added depending on the type of device you are using. For more information about FPLMN and how to clear it - check out this article.
As an Onomondo user, you have the ability to alter a Network List by choosing relevant networks in the Network Marketplace to match your specific use cases and control your spendings on data, while providing your devices with maximum available coverage.
If you have any more questions about Network Lists, make sure to check out this guide or reach out to us at [email protected].