April 23, 2015
The alpha system originally developed in the early 22nd century, a direct response to the massive losses of data as governments, civilizations, server bank, and software companies crumbled and to the increasingly paranoid lockdown the burgeoning Gene Lord society kept on information and communications. Unsurprisingly, it is also the main source of historical data for the period; the information banks of the various Gene Lord societies went the way of their predecessors, destroyed or simply unreadable without the now-vanished encryptions and dead permission-holders.
The modern-day alpha network has changed somewhat: it is no longer a pure-text repository, allowing some voice and picture content, and the entire repository is no longer replicated across the entire network -- nodes periodically reset themselves, erasing anything that is tagged as having been copied to the central repositories, so most of the data will be at most a year or two old. But the essential structure remains the same. Content is uploaded to an alpha node; the node copies the data to any other node it is in contact with, or comes in contact with; anyone can download all the content from a given node and view whatever they choose. It's common practice to have an 'alpha', an unusual and easily searchable string or phrase, which others can use in any message they particularly want you to see. Of course, anyone who knows your code can search it and see your 'mail', or people can just randomly stumble across it at any time, so as a secret communication system it leaves something to be desired -- but as Hans notes, it's also extremely difficult to figure out where a message originated from and impossible to tell where it was received.
It's also less vulnerable to service disruptions than the more sophisticated systems and the gear to make an alpha node -- mobile or otherwise --- is extremely cheap, which is why it remains popular in places like Kieselburg.
(Note that there's a certain amount of tech blur going on here as well. Alpha repositories are not, by the standards of 2427, very large; a standard phone can become a node, allowing you to view and change content, and still have plenty of room left for the newest holo-games and all your vid-mail. And it's very typical for people to use the generic term 'alpha' for any phone/vid/holo/message service they happen to have, and frequently to use the same code across both those and alpha networks. People don't separate them mentally unless they're in a situation where they can use only the alpha network -- or when, like Hans and Penn, the differences are screwing them over.)