Panasonic KX-TVP50E Installation Manual page 298

MESSAGE MANAGER'S GUIDE
Note
If you hear "Call Forwarding not accepted. Please check the destination number",
the forwarding setting has not been completed properly at the PBX, possibly because
a nonexistent extension number has been entered as the destination. It is also possible
that the model of the connected PBX does not support the Remote Call Forwarding
Set, or its software version is lower than required; for more information, consult your
dealer.
298 Installation Manual