Panasonic KX-TVS120 Installation Manual page 364

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 feature, or its software version is lower than required; for more information, call
National Parts Center at 1-800-833-9626.
364 Installation Manual