I'm trying to connect to the NB-IoT network in my city, and I've already gotten the hardware as well as the confirmation that there is an NB-IoT cell tower in my neighborhood.

Naturally, there's an NB-IoT SIM card as well that is used to connect to the network, but I have not received that unfortunately.

Question: Is it somehow possible to connect to that guardband network which piggybacks (CMIIW) of the LTE network by using a 4G/LTE SIM card though? Since if I recall correctly, the base station only has its firmware renewed so that the NB-IoT radiowave can be recognized.

Additional question: There's SIM 800 and SIM900 shield for GSM modules. Can I theoretically use a 4G/LTE SIM card and utilize the 2G Network? I'm not quite sure I can just ask the kiosk owner next to my house the question "Hey is this data only 4G card 2G compatible?" cause I'm also not quite sure what that means.

So, if I were to use the 3G 4G module, like this one for example...the communications type is LTE, but the transmission type is GPRS and EDGE (and HSP+ as well as LTE), according to the data sheet. AFAIK, that transmission is the architecture of the network as it travels from the base station towards the internet (CMIIW), but would our type SIM card be relevant for that?

One more question I've never used a module with an embedded SIM before. How does that work? Am I subscribing to an ISP until a certain time? I'm rather new with cellular modules for microcontrollers, I only understand the connection service like how our mobile phones work.

  • 1
    Regarding your bonus bonus question. Usually ISPs don't care what kind of device you put the SIM into in general. A primary SIM card is usually able to support data and phone services while secondary cards often only support data. That being said it's essentially freely configurable on ISP side. In corporate settings that is widely used and most SIM cards that are built into industrial machines for service purposes are only able to send SMS (sometimes receive SMS). They can't use any other services. (1/2) – Helmar Nov 15 '17 at 13:10
  • If you want to know the capability of your SIM card and maybe angle for a better contract you'll have to prod your ISP/card issuer. (2/2) – Helmar Nov 15 '17 at 13:10
up vote 3 down vote accepted

You probably already know more about this, than even 3GPP does. Looking at their documentation, which is not to be read by the faint-harted, it seem that NB-IoT is using a new special category of the LTE Advanced Pro, in 3GPP Release 13. Again, note that release 13, does not mean LTE UE Cat 13, but the new category NB1. For further info, look here and here, and links therein.

So this seem to indicate that in practice, your hardware (and its radio firmware) must support LTE Cat NB1 and you must use a SIM compatible with that network. Thus, for the low-end hardware you mentioned, it is probably not supported. If you want to do more magic than that, you may consider getting into SDRs.

Q: What is an embedded SIM (eSIM/eUICC)?

A: Please post your questions separately... But, it's just a software emulated SIM, where the SIM file system is all handled by software. (Did you even bother to google for it?)

  • Thanks! >You probably already know more about this, than even 3GPP does. Their release documentation is really hard to comprehend. I've went to a few sites and made my own conclusions as to what the Rel. 13 is about. My question about how the NB-IoT "uses LTE Network" is based on the "Marketing" brochure by a telco here in Germany which is also echoed at different blogposts which refer to Rel.13, but never explicitly proven For the second thing, I meant on using that hardware for M2M connection using 2G Network, not NB-IoT. So I guess I'm asking for backwards compatibility – akimbo_dragon Nov 20 '17 at 13:51
  • And yes, forgive me for not googling first about the emulated SIM. I'm intrigued now however, as to why GSMA released it as something new for the automotive industry, when embedded SIM has technically been around since...2006? Thank you again for the tip. – akimbo_dragon Nov 20 '17 at 13:58

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