Important Note: The Article itself isn't really notable but it sites the
The German newspaper Frankfurter Allgemeine Zeitung as it's source which is also what will be quoted.
https://archive.is/BKxIU
>NATO has for the first time since the Cold War ended again on a direct line to the Russian military. “NATO and the Russian military authorities maintain communication links. Both the Supreme Commander for Europe as well as the Chairman of the NATO Military Committee have permission to sit with their Russian counterparts in connection “, said the alliance with the request of the Frankfurter Allgemeine Sonntagszeitung. The communication channels are always open and would be tested on a regular basis, it said.
>NATO did not specify when the system was activated. From a national delegation told the FAS that the Russian side in the past week, contact numbers had been sent. The operation was classified as “secret”. It goes back to an initiative of the German Foreign Minister Frank-Walter Steinmeier (SPD). This had suggested in December, given the tensions related to the crisis Ukraine again set up a regular service for emergencies."
BTW for the part of when it was not specified this is from 12 Jan. 2004 http://www.nato.int/docu/update/2004/01-january/e0112a.htm
https://archive.is/huLDK