Zultys recommend for voicemail storage, reserve 30MB HDD space for 1 hour voicemail. For 400 hours voicemail storage (MX250 voicemail size), it will require 12GB of HDD space.

For call recording, Zultys recommend reserve 80MB HDD space for 1 hour call recording. Detail of how to calculate the 80MB HDD space could refer to attached "Call Recording" document, section 8.