pin 1-hook 
2-mic ground 
3-ign. 
4-detector audio out 
5-mic hi 
6-external speaker output a 
7-switched voltage 1 amp max 
8-PTT 
9-remote speaker output 
10-horn alert out 1 
11-horn alert out 2 
12-external speaker output a 
13-external speaker output b 
14-external speaker output b 
15-ground 

13/14 is for PA speaker 
9/12 jumper for internal speaker to work