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

Original Article ↗ Hacker News Discussion ↗

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.