Can you use an eSIM with Nb-IoT and CAT-M?

LTE-M and NB-IoT: the core difference

LTE-M and NB-IoT are both 3GPP-standardized LPWAN technologies built for low-power, wide-area IoT connectivity, but they optimize for opposite priorities. LTE-M prioritizes speed and mobility, supporting handover between cell towers and richer data, while NB-IoT prioritizes coverage and ultra-low power, trading bandwidth and mobility for deeper penetration and longer battery life. 

Together, the two technologies passed 1 billion active global connections at the end of 2025, according to GSMA, a decade after the GSMA's Mobile IoT Initiative set out to standardize licensed LPWAN. Which one fits a given device is a design decision made early, since it shapes the modem, the antenna, and the battery budget from day one.

Is CAT-M1 the same as LTE-M?

Yes. Cat-M1, sometimes written CAT-M or LTE Cat-M1, is the 3GPP device category that defines LTE-M. The names describe the same technology from two angles: LTE-M is the network-level standard, while Cat-M1 is the modem or device category that implements it, in the same way "4G" and "LTE" describe the same generation of network from different vantage points. 

You'll see both terms used interchangeably across spec sheets, module datasheets, and carrier documentation, so treat LTE-M and Cat-M1 as the same thing when comparing options or researching a module.

LTE-M vs NB-IoT: full spec comparison

Battery-life figures are typical industry benchmarks for infrequent, small-payload reporting and vary by duty cycle, network configuration, and module vendor.

Use cases: when to reach for each technology

• LTE-M: fleet management and vehicle telematics, asset tracking on the move (pallets, containers, trailers), wearables, point-of-sale terminals, and any application needing real-time or near-real-time data.

• NB-IoT: smart meters (gas, water, electricity), environmental sensors, smart parking, waste-bin fill sensors, utility monitoring, and other static, deep-indoor, or underground deployments where devices report small amounts of data infrequently. See Low Bandwidth Connectivity for how Pelion supports both.

eSIM and NB-IoT: why profile switching doesn't work today

Questions in the IoT connectivity space are often based around the capabilities of eSIM and what technologies it can currently support. One that is particularly common is if you can combine the profile swapping capabilities of an eSIM with the ultra-efficient NB-IoT network technology.

In theory, you can put an NB-IoT profile on an eUICC, however, at present there is no viable method to change profiles which defeats the purpose of using eSIM and in doing this, would put your device at a disadvantage. What’s currently stopping the pairing of NB-IoT with eSIM is the technology in between. NB-IoT does not support SMS protocols of which eSIM relies on to function - the two conflict in the way they operate. An eSIM changes profiles when an SMS is sent to the device which is then received, and a separate SMS is then sent back. Therefore, without SMS there would be no communication between platform and device. Hence why NB-IoT would not allow for a profile change in its current form.

eSIM and NB-IoT evolved independently to solve different problems in the same space and both made significant advances in mobile standards.  NB-IoT (and other LPWAN tech) focuses on battery usage and device security. NB-IoT is also mobile operator driven and best for very low data applications whereas eSIM focuses more heavily on the need to remove the physical sim card as IoT devices become smaller and more constrained. eSIM does also focus on security but on a hardware, level as opposed to a network level like NB-IoT which has what has potentially created a disconnect between the two technologies. An interesting observation by our Director of product is that when new technologies get created to serve the IoT space, the GSMA usually makes it work together but this didn’t happen for NB-IoT which could also have played a part in the disassociation.

It's a common train of thought in the IoT community that NB-IoT will stay as is but eSIM will evolve to better compliment and serve NB-IoT. The SMS protocols that eSIM relies on is a relatively old protocol and it makes sense to abandon older tech for its newer counterpart. If there is an evolution in remote sim provisioning that bridges the gap between the two technologies, then it is thought that eSIM could massively accelerate the scale and adoption of NB-IoT. If this happens it could result in some really great solutions taking advantage of the complimentary benefits of both technologies, but for now, this is just speculation.

Today, if you want an eSIM based LPWAN solution your best option is LTE-M and CATM1 technologies. LTE-M based technologies support SMS is and as previously stated, this is what allows the connectivity technologies and eSIM to co-exist and work together. In using eSIM with CAT-M a device can also achieve higher band width as well as being able to change profile should the IoT device require it.

To briefly summarise, we recommend using CAT-M if your device needs to be able to perform profile switching either now or in the near future. Whilst it may be possible to use NB-IoT and eSIM together there is no guarantee that the advancement in remote sim provisioning will even happen. Therefore, the IoT community must bear this in mind when considering NB-IoT as a connectivity option if eSIM is either required or a desired factor.

The IoT space has moved on a lot from physical sim card that catered for voice and SMS to being heavily data driven and focused on the future proofing of devices. As always, when putting together a solution we recommend carefully assessing the priorities for your deployment - both shorter and longer term. Once those priorities have been decided, then it is time to choose your technology. For example, if your priorities are heavily focused on future-proofing and retaining maximum flexibility then eSIM is the answer and that means for now, you will not be able to take advantage of NB-IoT. Alternatively, if what you care about is keeping costs low and minimising the power usage of your IoT device then NB-IoT can still be a great choice, it just means sacrificing flexibility. Ultimately, there is no one-size-fits-all answer. If you want help spec’ing the right solution the Pelion team is always happy to help.

For a foundation level insight into eSIM, please read our eSIM basics blog at What is eSIM for IoT - the basics - Pelion.

One important update since this was first published: the evolution in remote SIM provisioning this article speculated on above now has a name. GSMA's SGP.32 standard, finalised in 2023 and rolling out commercially through 2025 and 2026, defines a new architecture, the eSIM IoT Remote Manager (eIM) and IoT Profile Assistant (IPA), that provisions eUICC profiles over IP instead of SMS. 

Because it doesn't depend on SMS, SGP.32 is designed to work across NB-IoT and LTE-M, addressing the exact limitation described above. Adoption is still early and depends on your module and network operator supporting SGP.32, so validate this with your hardware vendor before committing a design to it. Until then, LTE-M paired with SGP.02-based eUICC remains the broadly-supported, lower-risk choice; see Consumer eSIM for IoT for how Pelion's embedded eSIM option works today.

Decision framework: LTE-M or NB-IoT?

• Choose LTE-M if your devices move, need voice or VoLTE, send larger or more frequent payloads, or need to support eSIM profile switching today.

• Choose NB-IoT if your devices are static, need the deepest possible indoor or underground coverage, and battery life matters more than data rate or flexibility.

Either way, validate country and carrier coverage before locking in a design: both technologies are widely but not universally deployed, coverage maps differ by operator, and a device designed around one may need a fallback plan in markets where only the other is available. 

This matters more given how fast the safety net is disappearing: GSA counted 313 completed, planned, or in-progress 2G and 3G network switch-offs across 89 countries by June 2026; see 2G/3G Network Sunset for what that means for legacy devices. Whichever technology fits, Global IoT SIM gives you a single SIM that can be provisioned for either.