The form factor question arrives late. Hardware is picked, the enclosure is tooled, the launch date is set, and someone asks whether the units should ship with a removable SIM or a soldered eSIM. By then the answer has already been narrowed by decisions nobody thought were connectivity decisions.
Worse, the debate gets framed as old versus new. It is not. Removable SIM, eSIM, and iSIM are three ways to carry the same subscriber identity, and the right one depends on where the devices go, how long they stay there, and who has to touch them afterwards.
All three hold the same thing: a subscriber identity, credentials, and the network profile that lets a device attach to a mobile network. The difference is the physical package and how the profile gets on and off it.
A removable IoT SIM is a plastic card in a tray, in 2FF, 3FF, or 4FF form. The profile is written at manufacture. Changing operator means changing the card, which means someone stands next to the device.
An eSIM is a chip soldered to the board, usually in the MFF2 package. Profiles are downloaded over the air onto it. The hardware stays put and the operator changes remotely.
An iSIM moves that same function into a secure enclave inside the device's cellular modem or system-on-chip. No separate component, no solder joint, less board space, lower power draw. Provisioning works the same way as eSIM.
Note the split. Removable versus soldered is a hardware question. Locally provisioned versus remotely provisioned is a software and operations question. Most teams conflate the two and end up choosing hardware to solve an operations problem.
| Capability | Removable SIM | eSIM (MFF2) | iSIM |
|---|---|---|---|
| Physical form | Card in a tray | Soldered chip | Inside the modem or SoC |
| Operator change in the field | Physical swap | Over the air | Over the air |
| Vibration and moisture tolerance | Weakest point is the tray | Strong | Strongest |
| Board space and power | Largest | Small | Smallest |
| Local profile for roaming rules | Requires a site visit | Remote download | Remote download |
| Unit cost at volume | Lowest | Higher | Bundled into the modem |
| Field recovery when a profile fails | Swap the card | Depends on the fallback profile | Depends on the fallback profile |
| Modem support in 2026 | Universal | Broad | Limited to newer modules |
Permanent roaming is the constraint that decides most multi country deployments, and it has nothing to do with form factor until you need to react to it.
A device that attaches to a foreign network and never goes home is roaming permanently. Several markets restrict this, through regulation, through operator policy, or through both. Turkey, Brazil, India, China, Nigeria, Saudi Arabia, Qatar and Russia all have restrictions of one shape or another, and the EU has its own rules on how long a roaming arrangement lasts. Enforcement is rarely a letter. It is a fleet that stops attaching, in one country, on a Tuesday.
If your devices stay inside one regulatory bloc for their whole life, a removable SIM handles it. If they cross borders, get resold into markets you did not plan for, or sit in a country that later tightens its rules, you need the ability to load a local profile without dispatching an engineer. That is the argument for remote provisioning, and it is an operations argument rather than a hardware one.
Count the cost of one truck roll in your worst location. A charge point in a car park is reachable. A sensor on a wind turbine, a tracker inside a sealed trailer, a meter in a locked substation, a telemetry unit on a vessel at sea, none of them are.
For those, a SIM tray is a liability twice over. It vibrates loose, it lets moisture in, and it makes an operator change a physical journey. Soldered eSIM or iSIM removes both problems at once.
For devices in an office, a warehouse, or a vehicle that returns to a depot every night, the swap cost is an hour of someone's time. The argument for soldering is much weaker.
iSIM needs modem or SoC support, and in 2026 that means a newer module. If your bill of materials is fixed around an existing modem, the decision is made for you. eSIM support is broad but not universal, and the memory available for stored profiles varies by chip. Check how many profiles the eUICC holds before you design an operations plan that assumes four.
Remote provisioning for IoT used to inherit a specification written for phones. It assumed a user interface, a person to tap through it, and a device with enough resources to run the full client. Constrained IoT hardware has none of those.
The GSMA SGP.32 specification addresses that directly. It splits profile management so a fleet operator drives it from a server rather than from the device, and it works on devices with no screen and no user. For anyone managing thousands of units across borders, this is the difference between remote provisioning as a demo and remote provisioning as an operational routine.
Modem support for SGP.32 is still uneven in 2026. Confirm it against your specific module rather than the vendor's platform page.
The pitch for eSIM is portability. Swap operator over the air, keep your leverage, avoid lock-in. That holds only when the profiles are actually available to you.
An eSIM tied to one provider's platform, with no contractual right to download a competing profile, is a soldered lock-in with better marketing. Before you commit, get three answers in writing. Whose keys control the eUICC. Which operator profiles you have the right to load. And what happens to your fleet's profiles if you leave.
Ask the same of any provider you compare against. A provider that answers plainly is telling you something useful. So is one that does not.
Mixed fleets are normal. A hardware generation running removable SIMs alongside a newer generation on eSIM is a sensible outcome, not a failure of planning, as long as one platform manages both.
IXT supplies all three form factors on the same subscription, so the form factor decision stays a hardware decision instead of a provider decision. One SIM covers 600+ mobile networks across 190+ countries, and IXT supports local IMSI options in key markets to reduce permanent roaming risk.
Everything sits in one CMP: activate, suspend, group, and monitor every unit in real time, whichever form factor it shipped with. IXT runs its own mobile core built for IoT, which is what makes profile and routing control direct rather than dependent on a partner platform.
Not for every deployment. Removable SIMs remain the lower cost option for reachable devices inside a single market. eSIM wins where remote operator change and physical durability matter.
It gives you the mechanism to load a local profile without a site visit. The commercial access to that local profile comes from your provider, not from the hardware.
The eSIM is the hardware. The eUICC is the software architecture on it that holds and switches profiles. A soldered chip without eUICC capability is not remotely provisionable.
It runs in a certified secure enclave inside the modem or SoC, isolated from the application processor. The security boundary is comparable to a discrete element.
The device falls back to its previously active profile, which is why the fallback profile deserves as much design attention as the primary one. On a removable SIM the equivalent recovery is a physical swap.
No. Hardware generations differ and product lines differ. What matters is that one connectivity platform manages all of them under one contract.
Pick the form factor your hardware and your service technicians live with, then pick a provider that lets you change operator without changing the hardware. Ask us how it works for your deployment. Book a demo at ixt.io.