DebugMux is a vendor specific interface exposed by nearly all old
Sony Ericsson phones and modems. Similar to the Qualcomm's Diag
interface, DebugMux can be used to obtain logging messages from
different sub-systems, including the baseband.
Unfortunately, Sony Ericsson never published any documentation
describing the protocol. All information was obtained by analyzing
serial port traces and reverse-engineering DebugMuxSrv.exe.