Using FreePBX 126.96.36.199 / Asterisk 16.21.1 on Raspberry Pi 3B.
I have a lot of Grandstream phones (several models, including GXV3380, GXP2170, and DP722). These phones have a built-in “Intercom” feature that adds these headers to the SIP
Call-Info: <sip:IP.ADDRESS>;answer-after=0 Alert-Info: <sip:IP.ADDRESS>;info=alert-autoanswer;delay=0
I also have the FreePBX Paging/Intercom module set up, so I can do paging using the
*80 feature code, but my (very non-technical) users want to be able to just push the intercom button on the phone “because that’s what it’s there for.”
If I understand correctly, the reason this doesn’t work is because FreePBX does not copy the incoming
INVITE headers into the outgoing
INVITE that is sent to the other phone. When I use
*80, the outgoing
Alert-Info headers, but when I press the Intercom button, the outgoing
INVITE does not have those headers. It seems that the simplest way to implement this would be to allow FreePBX to detect those headers and copy them into the new INVITE.
Another discussion on this forum from 2015 (I can’t post the link, but search for “Preserve Alert-Info header”) seems to be asking for the same thing, and I was wondering if there’s any new/better way to do this that has been made available in the last 6+ years.
In the “Advanced Settings” section, I see the “Internal Alert Info” settings, which is described like this:
Alert Info to use on Extension to Extension Calls. ‘Inherit’ will use the previously set Alert Info,‘Unset’ will remove the previously set Alert Info.
The value defaults to
inherit. It seems to me that this setting already describes what I am trying to do, but looking at the SIP messages (using sngrep) shows that it clearly doesn’t do what I expect.