One thing I can see is that neither of the devices
send a SUBSCRIBE with
line-seize Event. They rather just subscribe to the call-info event, and
in the oubound INVITE, they don't send a Call-Info header either. Is
this mandatory for the SCA module to work?
It sounds like they're not configured for SCA properly.
Can I send you a pcap in private?
Please do, and I can confirm from the signaling whether or not the sets are properly
configured.
-- Jorj