This a MLAA? If so what are 1 and 2 programmed to do? Also check this under VM Options if they don't have a mailbox
Allow Transfer To Any Number
Enable this option to allow the Auto Attendant to transfer calls to any destination in the system whether or not it has a mailbox. To narrow the scope of allowable destinations, use the accompanying field, "Restrict Number that Begin with e.g. (6,8,9)."
To only allow transfers to extensions that have a mailbox, use the default setting, "Disabled."