SMS gateway

The system that moves messages between the internet and carrier networks, connecting applications to the SMS world.

An SMS gateway translates between internet protocols (HTTP APIs, SMPP) and the signaling that carrier networks speak. When a platform sends your verification code, it hands the message to a gateway, which routes it hop by hop toward the destination carrier.

Route quality between gateways explains most delivery variance: the same service's code can arrive in five seconds via one route and never arrive via another.