Pass-through Alert-Info header from phone

[PitzKey (Itzik)]

@kohenkatz

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 INVITE has Call-Info and 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.

FreePBX/Asterisk is a B2BUA, so it creates a new call and copies little to no information from the headers that are needed for the second call.

If you want, you can use the predial hook to check if these headers are present and apply them to the new channel.

@kohenkatz

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.

Inherit applies if there is already an Alert-Info header on that channel. In your case there are no Alert-Info headers on the new channel.