Hi, Yes basic voicemail on Mitel 5k will support UM also it can now expand upto 32 ports, if on a CS a ps1 is required to get to 32 ports.
Also as of V5 the basic VM will co-exist with a Nupoint. HX controller will need a PS1 if it has a high call rate.
Each Mitel 5K with PS1 supports max 250 mailboxes with UM. Without PS1 100 mailbox
