Hey motamman , thanks for writing in!
Sorry to hear you’re having a rough time with connectivity on Tachyon - we definitely understand the frustration when things don’t “just work,” especially for data-intensive projects like yours.
You’re right that the lack of a physical SIM slot can feel limiting. With very few exceptions (Google Fi being one), most modern networks, especially the ones embracing IoT, are shifting toward eSIM-based provisioning. In our case, removing the full-size SIM slot was both a design and a space-saving decision: it’s a surprisingly large component, and we wanted to maximise the available board area for compute and I/O.
That said, we do have an internal MFF2-to-4FF adapter PCB that attaches neatly to the secondary SD card slot on the board. It’s compact and relatively straightforward to solder if needed. While we don’t offer these as standard, I’d be happy to check if they’re available for sale - and if not, we’d be glad to send you one directly.
Regarding alternative connectivity: one of the big upsides of eSIM is the flexibility to bring your own data plan. For example, I recently used trip.com (Singapore-based travel portal, not affiliated with Particle) to get a 7-day regional cellular plan that worked across multiple Asian countries. I provisioned the eSIM directly onto a Tachyon using our public documentation - it just requires an RSP URL / activation code. It’s surprisingly straightforward to get access to a massive variety of consumer focus plans that are allowed to work on devices such as Tachyon out of the box.
Now, about Google Fi. It’s true that Google does some pretty tight validation on what devices are allowed to use Fi, particularly when it comes to eSIM. The profiles are managed exclusively through the Google Fi app on Android, and it’s not possible to extract the RSP link from that process without deep ADB log inspection. That’s by design. Some older Android phones still allow physical SIM use, which can be a workaround, but even then, using Fi in non-approved devices may be against their terms of service, and there’s always a risk of the SIM being deactivated. So I’d tread carefully there.
If you’re open to exploring other providers, there’s a wide world of eSIM plans out there, many with permissive usage terms for data-heavy deployments. Lastly, if this is commercial focused, talk to us! We have access to a lot more plans globally than we have exposed so far.
One final thing: have you tried activating the built-in cellular on your Tachyon? The first three months of data are included for free - just a small thank you for being an early adopter. It’s a quick way to get started, and it’s surprisingly liberating to throw the device in a bag and walk around without worrying about tethering.
Appreciate you sharing your experience, and I hope Tachyon proves useful for your project. Don’t hesitate to reach out if you want to explore any of the above in more detail.
Cheers,
Nick.