# APN configuration methodologies

With eUICCs, users can switch between multiple connectivity profiles. Since the profiles can have different APNs, creating a robust APN change methodology is important. Here are some ideas on how that could be achieved:

## APN library <a href="#apnconfigurationmethodologies-apnlibrary" id="apnconfigurationmethodologies-apnlibrary"></a>

Building an APN library locally on a device using ICCID & IMSI prefixes as a mechanism can make operational workload much lesser.

* Should implement a mechanism on devices to check ICCID and IMSI and set the APN
* Should be able to update APN library on devices when a new profile type is used - preferably across the fleet of devices

## On-demand APN configuration <a href="#apnconfigurationmethodologies-on-demandapnconfiguration" id="apnconfigurationmethodologies-on-demandapnconfiguration"></a>

Building a mechanism to update the APN Over-The-Air via a non-data channel (e.g. SMS) can help keep complexity on devices to a minimum and manage APN configuration only when required.

* Should be able to communicate via SMS with the devices
* Should have a good understanding of which profile is active at a time (this can get little complex in cases of fallback/ switchback profiles)

## Hybrid methods <a href="#apnconfigurationmethodologies-hybridmethods" id="apnconfigurationmethodologies-hybridmethods"></a>

Building hybrid methodologies customized to specific use cases can help keep solutioning practical.

An example is to keep a list of APNs on the device that can be updated Over-The-Air and rotate between them in case of consistent data connectivity issues. For 2 profiles a simple “fallback APN” logic could be:

* Use Default APN 1 for profile 1 - data fails
* Use Fallback APN 2 for profile 1 - works. Mark this APN as default & APN 1 as fallback.
* Use Default APN 2 for profile 2 - data fails
* Use Fallback APN 1 for profile 2 - works. Mark this APN as default & APN 2 as fallback.

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