Blocked number from main company reception desk can not be blocked with receptionist backups

Unwanted Caller, reaches main company number at the reception desk. Who has actual reception phone (Yealink T46S) and Office@Hand Desktop App. She blocks the number = works fine (except there is a 30 phone number limit). Does not work when she does not answer the phone and the call goes to her two backups. One backup has a T42S and the other uses desktop application. When the call is routed to them, does not show a caller-ID and as a result they can not add this unwanted phone number to their own block lists.