CME can be integrated with Cisco Unity, it is more or less as an integration with Call Manager except the fact that you must every setting in the CLI mode. Let’s see a kind of basic config:

!
telephony-service
voicemail 5555
!
ephone-dn 10
number 1234
call-forward busy 5555
call-forward noan 5555 timeout 10
ephone-dn 16
number 5566
mwi on
ephone-dn 17
number 5577
mwi off
ephone-dn 20
number 5555
name “VM-Port 1”
preference 0
no huntstop
ephone-dn 21
number 5555
name “VM-Port 2”
preference 1

no huntstop
ephone-dn 22
number 5555
name “VM-Port 3”
preference 2

no huntstop
ephone-dn 23
number 5555
name “VM-Port 4”
preference 3

!
ephone 20
vm-device-id “CISCOUM-VI1”
button 1:20
ephone 21
vm-device-id “CISCOUM-VI2”
button 1:21
ephone 22
vm-device-id “CISCOUM-VI3”
button 1:22
ephone 23
vm-device-id “CISCOUM-VI3”
button 1:23

So you can easily see that your config is trying to match the Unity port name and this is done with the command vm-device-id <<string>>. It helps also to register with Unity where you need the deviceId instead of a mac-address.