Heres an interesting website
https:// electrospaces.blogspot. com/
Gives definitions of code words used by intelligence agencies and also discusses some of the technology they use. One thing I noticed when looking around the site was something called THE RED CROSS HOTLINE.
"
The first hotline between North and South Korea became operational on September 22, 1971. The link was the result of the first inter-Korean Red Cross meeting held on September 20, which resulted in an agreement to establish two lines for direct telephone calls between the two countries."