Until last year, work had Mitel 5212 softphones as the main devices on desks. This was the case since 2008, and was apparently high time to replace them. As they had nowhere to go but the bin, I grabbed a few in the hope to use them at home. While Mitel has a proprietary protocol (MiNET), they also support standard SIP through another vendor firmware, which allowed me to add a few more physical phones behind my FRITZ!Box.
PXE-booting OpenBSD is easy and well documented. Unfortunately, it is not the case when more than just one OpenBSD install has to be made available through PXE. Using PXELINUX for multiplexing purposes has potential but the documentation is scarce, unsuccessful, or require patching the PXE loader.