MCS-78xx hardware is end-of-life and end-of-support. Last sale dates were
~2010-2012. By CUCM 11/12, deployment moved to virtualized UCS C-series.
CUCM 15 is virtualized on BE6000/BE7000 appliances or UCS — there is
no MCS hardware in the supported deployment matrix.
Operating system reference here is VOS 2000.x/2003.x (Cisco's
Linux-based appliance OS at the time). CUCM 15 runs the modern VOS Linux
release, with a different version family entirely.