Intercom with auto answer problems

I’m running a fresh install of asteriskNOW and using 4 Grandstream gxp2000’s and 1 gxp2020. What I want to do is have the phones auto answer on page/intercom calls only and the user would have to pick up the phone on extension to extension calls and calls from outside of the pbx. I’ve set the phones to auto answer with call-info and this didn’t help as it auto answered on everything. I’ve searched for days and I can’t find anything to help me out on this. I did read at that I need to use SIPAddHeader(Call-Info: answer-after=0), but I’m not sure where that goes or how to use it. Any help would be GREATLY appreciated! Thanks!



It will go in your dialplan for the page as below for aastra sets

exten => _*55XXXX,1,Set(__SIPADDHEADER=Alert-Info: ;info=alert-autoanswer)
exten => _*55XXXX,n,Playback(connected)
exten => _*55XXXX,n,Page(SIP/${EXTEN:3})