as you know five and ascension take place at the same time, now we all thought five had no real story until there was a link in ascension on the red phones.
Now a question how the zombies in five get there?
Well heres what i noticed. 1. in ascension the russian soldiers are wearing same uniform in five and 2. the gersch device, if you look closely at a active gersch you can see these numbers (the same look as the ones in the red teleporter in five) and the characters quote things like where do they end up”
So my theory is, is that the team accidentally sent the zombies to five, also maybe gursch ment this to happen because of the cold war era