Multi-carrier compatible

The idea is that if carrier A 's line doesn't work, then carrier B 's line can be used.

There are several ways to achieve this, but the first is to obtain SIM cards from two telecommunications carriers and use both.

There are LTE modules that support two​ ​SIMs, and an increasing number of products that support LTE communication also have two​ ​SIM slots.

The second method is to use a roaming SIM that supports multiple carriers with one card.

One​ ​SIM card is compatible with multiple carriers, so if company A doesn't work, you can switch to company B, and if B doesn't work either, you can switch to company C.

Both methods are more expensive than single-carrier options, but demand is increasing for applications where customers do not want to stop using their services.

Buffer Link

Its main use is limited to uploading sensed information to the cloud, but the system works by storing data that cannot be sent during periods of communication outages in memory or elsewhere, and then sending it all at once after the communication line is restored.

You will need sufficient memory to store the data until the communication failure is resolved.

Additionally, some devices have mechanisms that allow data to be accessed via alternative means, such as Bluetooth or SD cards, so that data can be extracted even if the communication outage is not resolved.

Failover

This is a system that attempts to maintain communication by switching to other means of communication if the cellular line is down.

Alternatives include wired communications (such as LAN) and other wireless communications (such as Wi-Fi), but cellular communications are preferred in places where such communications are difficult to adopt.

In that respect, multi-carrier may be more realistic.

In the future, satellite communications are also expected to become an effective backup method.