Panasonic KX-TVM50 Installation Manual page 171

c)
Program the PBX so that it will direct overflowed calls to the VPS.
1)
Go to the "Groups-VM (DTMF) Group-System Setting" screen.
2)
Select "None", "Answer by Mailbox", or "AA" as the parameter for "Intercept Routing
to the VPS Sequence".
This parameter determines which DTMF command the PBX will send to the VPS in
order to select the desired service (AA, VM, Custom Service, etc.). If using a Custom
Service, select "None".
3)
Click "Apply" to save the changed data.
5.3 KX-TDA Series PBX Programming for Inband Integration
Installation Manual 171