Originally Posted by Nozza x360a
Three Man Army achievement (more details on how this is done)
Note: From what I'm gathering, this can't be attempted until all 3 of the characters have met and all have each others contacts. I've trying it before this and I can only call one of the guys at a time to hangout out. The other is always Busy. Plus this is only going through Michael as he has both Franklins and Trevors numbers.
I had only just done the Fame or Shame mission before attempting the Three Man Army achievement. So at that point Franklin and Trevor hadn't met.
What I did was, I called up Trevor first and asked him to hang out, then called Franklin. Went over and picked up Franklin first then Trevor.