Sorry, but I think that description of the "Three Man Army" should be corrected.
At least it didn't work for me.
So it says "This is the location of the person you have just called. Head there, pick them up and then call the other character".
The way it worked for me when I called one character, picked him up and then tried to call another one his phone was alsways busy, but if you call one character and then immediately another before picking them up everything worked perfectly.