[asterisk-users] Newbie Polycom: DND answered as "on the phone" instead of "not available"

[Lee, John (Sydney)]

I am using Polycom IP600 phone.  If I call a phone which has DND (do not
disturb) enabled, the message to the caller will be "The person on
extension ... is on the phone, please leave a message ...".

Is there a way to pick the "person ... not available" message instead?