a. 未列入电话簿的
在线英汉词典

ex-directory的短语、例句：

ex-directory adj (US unlisted) (of a telephone number) not listed in the telephone directory at the wish of the phone-owner (for reasons of security, privacy, etc) （指电话号码）未列入电话簿的（用户授意为安全、 私用等而不列入者）
an ex-directory number 未列入电话簿的电话号码
go ex-directory because of hoax telephone calls 因有电话骚扰而不将电话号码列入电话簿中.