question about a vista 20 system?

I had a guy installing a vista 20 i think and i ended up disconnecting it because first of all when it got tripped it is supposed to call my cell phone, and it did but it kept calling and calling and it would lock up my phone so i could not call in . not all the sensors worked properly because i think he used the wrong resistors on the ends. he mentioned something about my keypad being old and needing replaced. Unfortunately he died before we got around to fixing it. can anyone send me a wiring diagram and new keypad, or is this thing so outdated i should just get a new one