<shameless plug> I love this stuff. So much so that I spent years researching and writing a book about it: "Exploding the Phone", a history of phone phreaking

<shameless plug> I love this stuff. So much so that I spent years researching and writing a book about it: "Exploding the Phone", a history of phone phreaking and the telephone systems the phreaks hacked on, from 1950-1980. http://explodingthephone.com/ http://explodingthephone.com/ </shameless plug> Regarding MF being an informal or loose standard, it was described in detail in the the 1955 AT&T publication "Notes on Nationwide Dialing" (http://explodingthephone.com/hoppdocs/nond1955.pdf http://explodingthephone.com/hoppdocs/nond1955.pdf, pdf page 95) and the 11956 AT&T subsequent technical publication "Notes on Distance Dialing" (http://explodingthephone.com/hoppdocs/nodd1956.pdf http://explodingthephone.com/hoppdocs/nodd1956.pdf, starting pdf page 82) and then in subsequent editions of "Notes on Distance Dialing" (1968, 1975) and then in "Notes on the Network" 1980. It was also specified in several international standards (CCITT, now ITU). For those interested in this kind of stuff, this page will be of interest: http://explodingthephone.com/docs.php http://explodingthephone.com/docs.php Search of autovon docs: http://explodingthephone.com/search.php?q=autovon&sort=relevance http://explodingthephone.com/search.php?q=autovon&sort=relev... Some interesting stuff there because you get a sense of AT&T, FBI,, and NSA being worried about this stuff. Also, this particular hack is interesting -- it describes a clever technique called guardbanding to get into AUTOVON from the civilian telephone network: http://explodingthephone.com/docs/dbx1032.pdf http://explodingthephone.com/docs/dbx1032.pdf