Panasonic KX-TD816 Programming Manual page 247

ISDN extension numbers – [01 2 ]ISDN Extension Number Set
Voice Mail extension numbers – [118] Voice Mail Extension Number Set
Phantom extension numbers – [130] Phantom Extension Number Set
Floating numbers – [8 13]Floating Number Assignment
PS extension number – [6 7 1]PS Extension Number Set
Features Guide References
Direct Dialling In (DDI)
Integrated Services Digital Network (ISDN)
ISDN Programming
3.2 System Programming
247