a hot line

hotline

1. A telecommunications link, especially a telephone line, that provides fast, direct access to a source of information, confidential assistance, or emergency aid. We've set up a hotline for any potential witnesses to come forward with information about the incident.
2. A direct and immediate line of communication between the heads of different governments, used especially for or during an international crisis. The hotline between the U.S. and Canada has been in constant use after the terrorist attack at the border of the two countries.

a ˈhot line (to somebody)

a special telephone line to an important person, such as a president, etc. which is used in emergencies: The President of the United States spoke on the hot line with the Prime Minister about the crisis.
See also: hot, line