http://books.google.co.in/books?id=CPRVbYDc-7kC&pg=PA65&lpg=PA65&dq=perimeter+system+russian&source=bl&ots=vINI3HVuMt&sig=P3pZbt4ZPTq1EoUs4Hea1Tg_TnI&hl=en&ei=l7bFSorDFI2pkAWy2PA-&sa=X&oi=book_result&ct=result&resnum=2#v=onepage&q=perimeter%20system%20russian&f=false
One of the reserve communication channels created in the Soviet Union is the Perimeter system, which has been integrated in the battle management system. The Perimeter system includes command rockets for transmission of commands directly to strategic missile launchers. After the appropriate command has been received by the Perimeter system command post, the command rockets would take off and transmit the launch order and authorization codes continuously in flight over missile position areas for a period ranging from 20 to 50 minutes. This signal would make the launch of delivery vehicles possible even if all other lines of communication between the launcher and the outside world have been damaged. Silo missiles could be launched automatically, without any participation by the combat duty personnel at the regimental command station. The relay stations transmitting commands to submarines and bombers probably can also receive the signal from the command rockets of the Perimeter system, and the submarines and bombers can receive the signal directly as well.
The distinctive feature of the Perimeter system is the possibility of activating it before a nuclear attack is detected. When the system was being designed, it was assumed that the supreme commander might issue the command to activate it after a warning of the first signs of a nuclear attack. According to the original plan, later rejected, if the command station of the Perimeter system was activated in advance and did not receive the order to stop the combat algorithm within a certain period of time, the launch of the command rockets and the transmission of the order to deliver a retaliatory strike would be automatic. This was supposed to guarantee the delivery of the retaliatory strike in the event of the elimination of the top leadership while reserving the possibility of cancelling the order in the event of a false signal.
There is a report claiming that this reserve communication channel is still in place, and has not been removed. A former Soviet army professional Valery Yarynich is asserting this claim.
http://www.wired.com/politics/security/magazine/17-10/mf_deadhand?currentPage=all