How does it send caller ID?
My guess is that it is an after first ring system, not a line reversal system.
Does it use DTMF. Bell standards, or V.23, etc.?
Assuming it uses a supported standard, you need to set these two parameters to match what the PBX actualy uses:
[code]; Type of caller ID signalling in use
; bell = bell202 as used in US (default)
; v23 = v23 as used in the UK
; v23_jp = v23 as used in Japan
; dtmf = DTMF as used in Denmark, Sweden and Netherlands
; smdi = Use SMDI for caller ID. Requires SMDI to be enabled (usesmdi).
; What signals the start of caller ID
; ring = a ring signals the start (default)
; polarity = polarity reversal signals the start
; polarity_IN = polarity reversal signals the start, for India,
; for dtmf dialtone detection; using DTMF.
; (see doc/India-CID.txt)
If you are in the USA, my best guess is that you want the defaults, but that is only completely reliable when dealing with a real PSTN line.
Although it is fairly unlikely that anyone knows your intercom, providing the make and model would do no harm and would help if they do know it. It shouldn’t have been necessary to drag out of you that were using this with a PBX, not with a phone.