I've decided it would be a good idea to document how it was decided that hardening stops the "Christmas Call" encounter from appearing. Initial inspiration goes to the student in "Everyday Disco" encounter that says basic computer security measures could stop this viral marketing when you choose the dialogue option "Complain about viral carols."
First I'd like to thank Cryptodynamic who took it upon himself to first spade out the wacky suggestion that computer security measures could stop this virus by walking around the Quad with 50 hardening for establishing an upper bound for hardening values. This person walked around the Quad with a "Fang PDA" with the programs "Midgard protector," "shining barrier," and "updating firewall running." It is unknown how many turns he spent adventuring in the Quad. But, he did report that he did not encounter the "Christmas Call" encounter.
50 hardening, however, certainly isn't what people tend to have in mind when they think of basic security measures. I decided that it may be a good idea to see if there is a minimum amount of hardening necessary to prevent this virus from gaining a foothold into our comm systems. My first spade attempt involved adventuring with a "Fang PDA" with no programs running. During this experiment, I became frustrated by having the encounters "Horrible Poet" and "Student Selling Books" eating up my turns. So I decided to kill two birds with one stone by buying up her two remaining books which included "Survey of Modern Poetry" and then equipped "Survey of Modern Poetry." Now both encounters ceased to be. This whole ordeal took about 8 turns. I then continued to adventure in the Quad for about 15 total turns. No "Christmas Call" encounter.
I then decided it would be a good idea to set up a lower bound of when the "Christmas Call" encounter appears. I equipped the worst computer imaginable that had natural hardening, the "Safety Learntop." It has a natural hardening value of 5, and I had no programs running. I adventured in the Quad for 10 turns. Christmas didn't call.
Concerned that it may be hardware basic security measures that is stopping this encounter, I installed the worst software security measure I could think of at the moment onto a computer with no natural hardening. I installed "software firewall" to "old PDA." In retrospect, I probably should have installed "Midgard Protection Suite." Clearly it is the worst defensive software imaginable. With my subpar setup, I adventured in the Quad for 10 turns. Christmas didn't come a callin'.
Worried that something strange may be happening, I decided to adventure in the Quad with no hardening protecting my computer systems. My very first encounter was "Christmas Call."
If anyone is dissatisfied with my methodology or the evidence I have presented for the case that any amount of hardening protects against the "Christmas Call" encounter, I suggest first beginning by adventuring in the Quad with a computer with no natural hardening with the "Midgard Protection Suite" running. Merry Christmas everyone.