Panasonic NS1000 Manual page 158

Unified Messaging Access (MSG Playback)
Recording or playing back messages from the UM requires DSP Resource. For this
example, the following DSP Resource is required:
1.3 + 1 = 2.3 DSP Resources Required
Unified Messaging Access (2-Way Rec)
2-Way Recording requires additional DSP Resource and Conference Trunk.
For this scenario, the following DSP Resources are required:
2.3 + 1.5 = 3.8 DSP Resources Required
1.3 DSP Resource Usage (4)
DSP Cost
1.3
DSP Cost
2.3
DSP Cost
UM
DSP Cost
UM
1
G.711
1 + 0.5
G.711
IP-PT
IP-PT
IP-PT