An IoT gateway is a device that bridges sensors, controllers, or other equipment using local-area protocols to wider networks like cellular, Ethernet, or fixed-line broadband. It is the translation and aggregation point between equipment that speaks Modbus, CAN, BLE, Zigbee, LoRaWAN, or other specialist protocols, and the IP-based world of cloud platforms, MQTT brokers, and corporate networks.

In short: A typical IoT gateway combines a cellular or Ethernet WAN connection with one or more local-area interfaces, plus enough onboard processing to translate between protocols, buffer data, apply local logic, and forward results to a backend system. Examples range from small single-purpose gateways (Teltonika TRB145 bridging RS-485 Modbus to MQTT, for instance) to more capable industrial gateways with multiple interfaces, edge compute capacity, and full operating systems.

The line between an IoT gateway and an industrial cellular router has blurred in recent years. Many cellular routers, particularly Teltonika's RUTM and RUTC ranges, now include the kinds of protocol translation, MQTT publishing, and edge logic that used to require a dedicated gateway. For new deployments, the practical question is rarely "gateway or router" but rather "which device gives me the connectivity, the local-protocol support, and the edge processing I need, in the form factor and price range I can deploy at scale."

Where IoT gateways remain distinct is in applications with unusual local-area protocols (Zigbee, BLE Mesh, LoRaWAN concentrators), high edge compute requirements (video analytics, machine learning inference at the edge), or specialist physical interfaces (fieldbus systems beyond Modbus and CAN). For these, purpose-built gateways from vendors like Advantech, Eurotech, Lantronix, and Dell remain the right answer.