Extension Locked Out
In most cases it is likely that the phone handset is off of its cradle. Simply place the handset back on its cradle and it will clear itself.
Also check and see if the handset cord is plugged into the left side or not. Often we find they are plugged into the wrong jack - on the right side of the phone.
If that is the case then unplug from the right side and move to the left side handset jack.
You can also unplug the line cord from the wall jack and see if the problem clears itself.
If it does not it is time to call Biax Communications.