Using eSIMs with devices that only have a physical SIM slot via a 9eSIM SIM car

Original Article ↗ Hacker News Discussion ↗

Hardware adapters that store eSIM profiles on a rewritable physical SIM card are emerging as a workaround for devices without native eSIM support, from older phones and LTE routers to Linux laptops and Chinese-market iPhones. Commenters weigh the convenience and often lower cost of travel eSIMs against their downsides: single‑use QR codes, migration friction, carrier-imposed constraints, and lack of support in markets like China. The thread also touches on technical and policy angles, including GSMA’s tightly controlled eSIM provisioning, Wi‑Fi calling and roaming behavior, and open‑source tools that avoid proprietary apps.

Why use eSIMs in physical-SIM devices?

  • Common motivation: older phones, routers, IoT gear, laptops, or Chinese-market iPhones that lack native eSIM but are otherwise fine.
  • Travel eSIM providers and local eSIM-only offers can be much cheaper or more flexible than local physical SIMs, so an eSIM adapter lets these legacy devices access those deals.
  • Some want to use free or ultra-cheap domestic eSIM plans on non‑eSIM phones, amortizing the adapter cost quickly.

Travel, roaming, and cost comparisons

  • Many report that airport/tourist SIMs are often overpriced compared with eSIMs bought online; others find the opposite in parts of Asia, Africa, and Mexico where physical prepaid SIMs are far cheaper.
  • Typical pattern: use a cheap travel eSIM for immediate connectivity, then buy a local SIM in the city if it’s significantly cheaper.
  • China is a special case: physical SIMs are strongly tied to identity; some avoid local SIMs due to the Great Firewall, while others need local numbers for services.

eSIM provisioning, migration, and lock‑in

  • eSIM QR codes are often single-use and many travel eSIMs are strictly non-transferable; some carriers allow re-downloads or reuse, but policies vary widely.
  • Moving an eSIM between devices frequently requires carrier involvement, fees, or even in‑person visits; some plans block remote activation from abroad.
  • Criticism: this is less user-friendly than physical SIMs that can be swapped instantly and privately. Supporters argue the standard itself is fine; problems stem from carrier practices.

Adapters, tools, and FOSS ecosystem

  • Multiple physical-eSIM adapters exist (9eSIM, esim.me, 5ber, JMP, others). Reports vary: some find older products glitchy or overpriced; others praise newer ones as more reliable and less restrictive.
  • Some adapters rely on proprietary apps; others are compatible with open-source tools (e.g., OpenEUICC/EasyEUICC) and even allow Linux/Android-based provisioning.
  • There’s interest in SIM-based setups for scraping, multi‑modem mobile proxies, and SMS-to-API gateways.

Wi‑Fi calling, roaming behavior, and SMS quirks

  • Debate over whether Wi‑Fi calling incurs roaming: some carriers treat it like home usage; others geoblock foreign IPs or misclassify calls as roaming.
  • Technical notes: handover between VoLTE and VoWiFi complicates “no roaming on Wi‑Fi”; some networks infer location from last seen cell or IP.
  • SMS delivery while roaming can be inconsistent due to older interconnect models; newer “home routing” improves this but isn’t universal.

Opposite direction: physical SIM on eSIM‑only devices

  • Several ask for the reverse solution (physical SIM to eSIM‑only phones), especially for China.
  • Technically difficult because SIM keys are designed never to be extracted; suggested workarounds involve external modems or hotspots rather than true emulation.