I used to think an eSIM was basically a SIM card without the plastic. Then I started working on a data-only eSIM service and had to answer support tickets like "so what do you actually know about me?" It turns out the honest answer is more interesting than "nothing" and more reassuring than "everything".

So here's a plain walk through the identifiers involved, who sees each one, and what a no-KYC provider can and can't hide. Full disclosure up front: I work on Silent eSIM, so I'll use our setup as the worked example, but the plumbing is the same for every travel eSIM out there.

The four numbers that matter

EID. This is the ID of the eUICC chip soldered into your phone. It's 32 digits and it never changes, no matter how many eSIM profiles you install. You can find yours on iPhone under Settings > General > About, or on most Android phones by dialing *#06# .

ICCID. This belongs to the eSIM profile itself, not the chip. It's 19 or 20 digits and almost always starts with 89 .…