Adding Call-Info to SIP INVITE

I’m using FreePBX with SNOM phones
I want to be able to display on SNOM the picture of the user
So SNOM WIKI here say that I need to do this:
The SIP INVITE should contain the following SIP Header:

Call-Info: ;purpose=icon


Call-Info: icon=“

So lets say I have some web server and I will put there images for each exstention
Something like
Where XXX is the number of the extension

Now how can I make FreePBX to add this to SIP INVITE ?

I don’t think you can change the initial INVITE without hacking the binaries, however, you can add headers.

im sorry, i meant it will only change the Initial invite.