[Milsurplus] Milsurplus Digest, Vol 157, Issue 14

[Brooke Clarke]

Hi:

2600 Hz is part of the in-band signaling protocol used in the early days of the public switched telephone system and was 
it's weak point.
https://en.wikipedia.org/wiki/Blue_box
The military telephones are based on the public telephone system, but a few decades back.  So you will see military 
versions of public phone equipment.
http://www.prc68.com/I/phones.shtml#Mil

There's a similar problem now with the ESS7  system in that it assumes all the nodes are friendly and compliant, so ripe 
for hacking.
https://en.wikipedia.org/wiki/Signalling_System_No._7
https://www.theguardian.com/technology/2016/apr/19/ss7-hack-explained-mobile-phone-vulnerability-snooping-texts-calls

http://www.prc68.com/I/SpyingOnCellPhones.html

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html