an automatic phone system in which callers select options in response to recorded questions, so the system can direct them to the right person or department Users had to navigate an elaborate phone tree before reaching a counsellor. 用户必须先精心制作一棵电话树，然后才能与辅导员联系。
a list of the names and phone numbers of the people in an organization, arranged in a way that shows who should call whom in case of an emergency, etc.