ˌex-diˈrectory adjectiveadj British EnglishBrE TCTa person or telephone number that is ex-directory is not in the public telephone book 〔人或电话号码〕未列入电话号码簿的 SYN American English unlisted The number is ex-directory. 该号码未列入电话号码簿。
After several threatening calls, we decided to go ex-directory. 接到几个恐吓电话后,我们决定不再将号码列入电话号码簿了。
go ex-directory• They are constantly changing their numbers, or going ex-directory to stave off threatening calls.
From Longman Business Dictionary
ex-directoryˌex-diˈrectory adjectiveadj British EnglishBrE an ex-directory telephone number is deliberately not given in a public telephone bookSYN AmE unlistedYou can change your number and go ex-directory (=no longer have your number in the phone book).