Mobile IoT Deployment Map
https://www.gsma.com/iot/deployment-map/
Connection Options
NB – Narrowband
Very limited data limit. Intended for very small amounts, like smart meters etc.
Better global coverage
LTE-M
Better for more data, but not currently forced as part of the 4G spec, so you’re down to which carrier decides to support it in each country. In theory it will become part of the spec, so carriers would be forced to support it, but at the time of writing it still isn’t.
For now using this with 2G fallback is the better solution to ensure you have coverage, unless you are in a region when LTE-M has good coverage.
Connectivity resources
Data usage
LTE-M is capable of transferring really quite a bit of data, although its primary purpose says that it isn’t intended for that. Some companies argue that if you’re transferring more than say 5MB a month then its not the right technology to be looking it as this isn’t its purpose. However there are 25MB per month or 500MB total SIM cards available from vendors for LTE-M for example, so it seems you can use it in applications wanting more than 5MB a month.
Connections to Servers
Alternative to using HTTP POST for connections
LWM2M (light weight machine to machine) protocol that is defined by Open Mobile Alliance (OMA)
Less overhead than HTTP POST (no big header etc that needs to be sent)