SOLVED: Door intercom system calls freePBX > automatic webcam image load on Cisco 7975 phones - how?

How to start a script is described in this post

[from-trunk-sip-MyTrunkName]
;Run Script
exten => .,1,System(/path/to/your/script)
;Continue on to default “trunk handling” from GUI
exten => .,n,Goto(from-trunk,${EXTEN},1)
; end of [from-trunk-sip-MyTrunkName]

however, I need asterisk to start the script without interfering with the normal call flow.
Any ideas?

Here’s a link to an image, which shows the results of my showcam script collection :wink:
http://www.ip-phone-forum.de/attachment.php?attachmentid=77992&d=1411914351

Is async-agi the solution to my problem?

Thanks
Reinhard