MBIM is short for the Mobile Broadband Interface Model and is a USB-based protocol for host/device connections of desktops/laptops/tablets/mobile devices. The MBIM 1.0 specification that was ratified in 2011 supports multiple IP connections per USB interface, power-friendly, enables device-agnostic mobile broadband class drivers, drops the need for AT-commands and other crude control channel mechanisms, and minimizes overhead.
Thanks to recent ModemManager work, MBIM is now supported. Features of this initial implementation cover PIN unlock/change/enable/disable capabilities, 3GPP modem support (GSM, HSPA, LTE, etc), and basic connectivity support. Not covered yet are most of the side-features like SMS messaging, location data, and other features.
Aside from needing the very latest Git master of ModemManager, a new FreeDesktop.org-hosted "libmbim" library is needed as well for this Mobile Broadband Interface Model support.