by shoestring source: 9/11 Blogger Jan 12, 2011
A special backup network that allows communications between government and military agencies to continue during emergencies was “miraculously” switched on the day before 9/11, and so was already operational when the terrorist attacks in New York and at the Pentagon took place. The Special Routing Arrangement Service (SRAS) was, for reasons unknown, turned on for “exercise mode” on September 10, 2001, and was therefore ready to be utilized the following day, when there was a national emergency like that for which it was intended.
The SRAS is the responsibility of a little-known government agency called the National Communications System (NCS), which works to keep critical telecommunications functioning during emergencies and played a crucial role in the government’s response to the 9/11 attacks, helping to maintain and restore communications networks. Furthermore, the SRAS is related to “Continuity of Government”–a plan that was activated for the first time during the attacks.
SRAS TURNED ON FOR ‘EXERCISE MODE’ ON SEPTEMBER 10
Brenton Greene, the director of the NCS on September 11, told the 9/11 Commission that on September 10, 2001, “miraculously, the SRAS system was turned on for exercise mode and thus it was ready to function on September 11.” Therefore, when the NCS was required to assist the government’s response to the terrorist attacks, the “SRAS was already in exercise mode and operational.” 
The SRAS supports the highly secret Continuity of Government (COG) plan, which is intended to keep the government functioning in the event of an attack on the U.S.  The NCS’s involvement in COG was one of the agency’s three main programs. As Greene told the 9/11 Commission, “The main communications system of the country must be kept going or no one can communicate.”  The SRAS provides “a vehicle for continuity of operations by providing survivable communications linkages to federal and defense end users over the public network,” according to a Department of Homeland Security publication. 
Apparently describing the SRAS, Greene told the 9/11 Commission, “There is a separate network linking the National Coordinating Center and the major carriers and networks as a backup.” (The National Coordinating Center, in Arlington, Virginia, is the “operational arm” of the NCS.) This network “proved its value as a separate link on 9/11 because it coordinated network use between Network Operations Centers while the [telecommunications] network was saturated.” Furthermore, again apparently describing the SRAS, Greene said, “In the situation where Continuity of Government is put into play”–as was the case on September 11–“there is a communications system where no one can trace the site of the call on either end.” 
WAS THE NCS INVOLVED IN A TRAINING EXERCISE ON SEPTEMBER 11?
Greene apparently did not tell the 9/11 Commission why the SRAS was turned on for “exercise mode” on September 10. But a possible explanation that needs to be investigated is that the NCS was scheduled to participate in a training exercise on September 11. We know that the NCS was, in 2001, part of the Department of Defense.  And several U.S. military agencies are known to have been conducting exercises on the morning of September 11. For example, the North American Aerospace Defense Command (NORAD) was running its annual exercise, “Vigilant Guardian,”  and the United States Strategic Command (Stratcom) was holding its annual exercise, “Global Guardian.”  Might the NCS have been participating in one of these, or another exercise?
More at the original source. Click HERE