The underground information web the Brainers are so fond of, the Ethyrnet, is separate from official, Traders' Guild-controlled Holonet, although it is not impossible to infiltrate one from the other. Ethyrnet, used basically by every community, relies on innumerable private comms sender-receivers, their transmissions heavily scrambled to hide in the jungle of EM background noise. Ethyrnet is how Jack can contact us and all his tribes, it's how Black Market and Mutant Alliance communicate.