There was a time when all mobile broadband modems spoke AT commands over serial ports, and PPP was used to establish a network connection. Soon, each vendor ended up with its own AT dialect or, even worse, a completely new protocol: phonet, QCDM, QMI, WMC, MBIM... This talk is a general overview of these protocols, how and why they have evolved over time, and their current implementation and usage in Linux-based systems.