As someone who’s had some incidents with DSP code, the end of the recording sounds like it may be playing some part of memory that isn’t an audio buffer. I wonder if there’s actually a “DTMF injection” possibility here…
> shared it with a few people who Know Telephone before I posted it here, and their theory is that what we're hearing at the end is the audio path going open-circuit when the PC crashed. It probably blue-screened, and we're hearing the EM interference from the CPU or I/O controller hub as Windows writes a minidump, then begins waiting for a debugger to attach (the blerps at the end being scans for connected serial port, PCI, network or 1394 debug hardware)