This refers to FreePBX 2.2.0, Asterisk 1.2.14 and Aastra 480i firmware 1.4.1.1077.
FreePBX auto-generates extensions_additional.conf with the [ext-intercom] context containing a workable hands-free intercom section.
The problem is that the stock [ext-intercom] context won’t trigger the auto-answer-alert splash tone on Aastra 480i phones using firmware 1.4.1.1077. That firmware requires a special SIP header to activate the splash tone.
To make it work, you have to REPLACE line 7:
exten => _*80.,n,Set(__ALERT_INFO=Ring Answer)
WITH:
exten => _*80.,n,Set(__SIPADDHEADER=Alert-Info: ;info=alert-autoanswer)
Unfortunately, every time that you use FreePBX to maintain extensions, it overwrites the changes.
I would like to know where in the FreePBX code this context is generated. I might be able to modify my copy of FreePBX, if I could just find the right module and the code.
Thanks in advance for any suggestions!