When we talk about cellular modems we mean those relying on the 4G or 5G network. In the old days cellular networks established voice circuits much like the old telephone network. These days 4G and 5G are totally packet-based data networks, not all that different to gigantic WiFi networks.
4G-5G modems and routers are all powered by a chipset that is manufactured by a company like Qualcomm, Sierra Wireless, or Quectel. It’s this chipset, often referred to as the ‘cellular module’, which determines the modem’s capabilities over the cellular network.
One of the most well known features is the Device Category, which defines the way the modem communicates with the network. The first 4G modems were Cat-3 and later Cat-4, which meant they could connect with speeds up to 100 Mb/s and 150 Mb/s respectively. As the technology evolved we started to see Cat-6 modems in 2014, which coincided with the launch of Telstra 4GX LTE-Advanced, these modems could achieve speeds as fast as 300 Mb/s.
Today, a decade since the first 4G network, we have Cat-22 modems. These modems use techniques known as Carrier Aggregation, high order modulation, and advanced spatial multiplexing techniques to deliver beyond 2 Gb/s. You can learn more about these techniques in the resources section of the website.
Just as networks evolved to be faster, they also needed to evolve to be slower. While this might sound bizarre, device categories such as Cat-1, Cat-M1, and Cat-NB1 were implemented to provide more reliable communication over longer distances and use less power. These are known as NB-IoT and LTE-M modems which you can read more about by clicking its link.