The latest articles on DEV Community by willy (@willy032). https://dev.to/willy032 https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F4202790%2Fff840d4d-b95e-45b9-8563-9f74414bc3f5.png https://dev.to/willy032 en willy Fri, 30 Oct 2026 17:54:59 +0000 https://dev.to/willy032/what-an-esim-actually-is-under-the-hood-and-why-the-profile-is-just-a-downloadable-sim-4a06 https://dev.to/willy032/what-an-esim-actually-is-under-the-hood-and-why-the-profile-is-just-a-downloadable-sim-4a06 <p>Most travel-data advice is about price. The interesting part is mechanical: an eSIM is not a SIM at all, it is a downloadable profile written into the same secure element (the eUICC) that the physical SIM used to occupy. The operator side is what changes.</p> <p>How it works, briefly:</p> <ul> <li>The phone ships with an eUICC soldered in. It holds several profiles and switches between them without swapping anything.</li> <li>You scan a QR (or the operator pushes an activation code) and the profile is downloaded and installed on that chip.</li> <li>The profile carries the operator's IMSI and keys, so the network sees a normal subscriber. Roaming is handled by the operator's agreements, not by magic.</li> <li>Enabling or disabling a profile is a local operation: going back to your home SIM is a settings toggle, not a physical swap.</li> </ul> <p>The part people get wrong is that the eSIM is not a carrier, it is a container. Which network you land on, the throttling policy and the top-up mechanics all come from the operator behind the profile. That is why two "eSIM for Japan" plans can behave completely differently on the same handset.</p> <p>Longer walkthrough, including the activation flow and what happens when you switch profiles mid-trip:<br> <a href="https://www.tailsim.com/guides/how-esim-works/" rel="noopener noreferrer">https://www.tailsim.com/guides/how-esim-works/</a></p> <p>Tags are honest here: this is not a programming post, it is the networking side of travel data.</p> discuss travel willy Thu, 29 Oct 2026 10:58:22 +0000 https://dev.to/willy032/pando-the-largest-living-thing-on-earth-is-a-single-tree-kej https://dev.to/willy032/pando-the-largest-living-thing-on-earth-is-a-single-tree-kej <p>Pando, in Utah, is not a forest.</p> <p>It's ~47,000 quaking aspens sharing one root system — one organism, 43 hectares wide, roughly 6,000 tonnes, thousands of years old. The largest living thing we know of.</p> <p>Every autumn it turns gold all at once, because it's one tree breathing.</p> <p>It's also dying: deer and elk eat the new shoots before they grow tall enough, so nothing replaces the old stems. Parts of the grove are fenced off, and the new growth inside those fences is the only thing keeping it alive.</p> <p>Not dev-related at all, but a good thing to know.</p> discuss science