high mesa
this opinion is from an unqualified source with some small ipo experience. i once made about six site visits chasing a similar complaint. billx's suggestion was my first test.
my problems went away while i had cid turned off. if you think about it, cid information could be delayed 5-10 seconds during a normal pstn ring cycle. you may discover some ipo call routing instructions that start happening before cid is completely received resulting in your trouble symptoms. my final solution turned out to be a programming problem related to alternate call routing timing. do turn off cid trunk option as a test. that will not prove the trouble to be in either direction, but it may prove that it is connected to the solution.
good luck.

Last edited by dude; 08/31/19 08:09 PM.
HE SEEMS TO BE SAYING SOME KIND OF WORDS