What is network fallback?

Hologram’s next-generation Hyper SIM includes support for an innovative new capability called network fallback. Network fallback is a configurable intelligence layer that lives on the SIM card and enables automatic switching between linked eUICC profiles in the event of extended periods of network downtime.

Network fallback helps to ensure that Hyper SIMs that lose connectivity for any reason (lost coverage, network outages, unexpected roaming) can be quickly and automatically reconnected to the Internet without the need for manual intervention.


Why did we develop network fallback?

Although all eUICC SIMs are capable of storing multiple connectivity profiles, most require an Internet connection to switch between them, and help from your connectivity vendor to actually execute the profile switch. When devices experience gaps in connectivity, it’s not very helpful to have a backup profile on the SIM if you’re dependent on an Internet connection to enable it.

Network fallback solves this problem by giving every SIM card the intelligence to detect and track periods of downtime and independently complete a profile switch when extended periods of downtime occur. Our goal is to build the world’s most reliable IoT connectivity offering, which requires devices to have ready access to multiple profiles for carrier and route redundancy, and the intelligence to switch between them as necessary.


How does network fallback work?

The simplest way to think of network fallback is as a timer that communicating with the cellular modem and is constantly watching for extended periods without network connectivity. When the modem begins experiencing a period of limited or no service, the timer starts. Once the timer reaches a customizable threshold, it automatically executes an eUICC profile operation to enable the fallback profile and attempt to reconnect to the Internet. If it is successful in doing so, it let’s the Hologram platform know that a fallback event has occurred, and stays connected with the backup profile until it receives further instruction.

Here are some additional things to know about network fallback:

  • Network fallback supports multiple customizable trigger thresholds including some that are volatile (will reset if the device is restarted) and nonvolatile (can persist between device resets).
  • The default timer value for network fallback is 20 minutes
  • By default, network fallback also supports reverse fallback – switching from a backup profile to the primary profile – based on the same trigger conditions


What are the benefits of network fallback?

The biggest benefit of network fallback is a significant reduction in the duration of incidental loss of connectivity (from hours or days to minutes).

Although cellular networks are considered to be highly available and reliable compared to alternate wireless protocols (ex: Wi-Fi), periodic loss of connectivity caused by lost coverage, network downtime, or device roaming is inevitable. These outages may take hours or even days to resolve, stranding the device without connectivity without recourse. This downtime may result in lost data, lost revenue, or failures of mission critical operational systems.

Network fallback ensures that devices that get disconnected can reconnect quickly using an alternate connectivity profile so they can resume normal operation in minutes.


What are the primary use cases for network fallback?

There are three primary use cases for network fallback:

  1. Resiliency to downtime. As discussed above, product creators may wish to add and link a backup profile to their Hyper SIM with network fallback to attempt to automatically reestablish connectivity to prevent lost data or revenue in the event the primary profile loses connectivity.

  2. Regional profile selection. Many product creators have primary markets that drive the majority of their demand, and long tails of international customers that may benefit from an alternate connectivity solution due to cost or performance considerations. Stitching multiple profiles together with network fallback allows SIMs to automatically localize connectivity to the most effective profile without building and supporting multiple individual SKUs.

  3. Combining coverage footprints. In rare instances, Hologram’s connectivity relationships may not enable access to every carriers in a particular country using a single connectivity profile, or may provide more cost-effective access to the same carrier via a different profile. Linking multiple profiles together using network fallback allows devices to access the richest selection of carriers at the best possible cost, all on a single SIM.


Can I customize the behavior of network fallback on my SIMs?

Yes! Network fallback was designed with thoughtful defaults that work with most applications, but can be thoroughly customized to meet the needs of your application. Vectors of customization include:

  • Turning network fallback ON or OFF
  • Setting trigger thresholds for network fallback (20 min default)
  • Changing which profile is designated as the fallback profile
  • Turning reverse fallback ON or OFF


Which data plans from Hologram are currently compatible with network fallback?

As of June 2023, Hologram supports network fallback to global multi-carrier connectivity for all premium North American data plan offerings.



  • What circumstances can trigger network fallback?

    Network fallback tracks limited and no service status messages from the modem and evaluates them against a threshold that triggers the SIM to enable the backup profile. Limited and no service status events can occur in any of the following scenarios:

    • The network is not available (outage or coverage)
    • The profile is paused while the device is powered
    • The profile is blocked from accessing a carrier by the underlying steering for its connectivity plan

  • Can I add support for network fallback to SIMs that I’ve already deployed?

    The SIM intelligence that enables network fallback is signed and encrypted at the time the SIM is provisioned, and thus can only added at the time of SIM manufacturing. Support for network fallback cannot be flashed or added to SIMs previous generation Hyper or UICC SIMs from Hologram shipped prior to June 2023.

  • Which Hyper SIMs support network fallback?

    Network fallback is supported on all Hyper SIMs with the AFB SKU designation shipped on or after June 2023.


  • How do I know when network fallback has occurred?

    When devices reconnect to the Internet, they pass a callback to the Hologram platform to let us know it’s reconnected. This allows us to update the status of your SIM card.

    To find this information in your dashboard, open a device page for the SIM card and the new active profile will display at the top of the page.

    You can find history of these events by scrolling to the bottom of the page and looking for carrier and ICCID changes within the Recent data usage card.


  • Is there any risk that network fallback will brick or strand my IoT device?

    SIMs with network fallback and reverse fallback enabled are less likely to be permanently stranded than devices without it.

    Network fallback will only trigger in the event that a SIM is unable to connect to the Internet for extended periods of time. When reverse fallback is enabled (it is by default), network fallback will cycle between linked profiles until the device successfully reconnects to the Internet.

    For this reason, network fallback is a helpful tool to recover SIMs that are stranded from remote access, and will rarely if ever contribute to a SIM permanently losing network access.

  • How is network fallback different from multi-IMSI?

    The biggest benefit of network fallback over multi-IMSI solutions is that it provides the device with full route redundancy – an alternate networking path to the Internet. Multi-IMSI solutions typically house all alternate IMSIs within a single profile, which makes them susceptible to single points of failure in operator maintaining the multi-IMSI profile’s mobile core and connectivity infrastructure.

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