g'day mate. Respectfully, I'm from the USA, but I do have friends in Yackandandah, VIC.
I am new to the NEC SL2100. I have the system in a test environment. When I connect the SL2100 with the automated attendant to a regular POTS line, the system disconnects fine. If I connect the SL2100 with the automated attendant to a test extension of an Avaya IP Office system, it doesn't disconnect. Avaya IP Office extensions have positive disconnect. I use them for testing all of the time.
The interesting thing is, if I turn off the SL2100 automated attendant, and just have the SL2100 connected to the Avaya IP Office extension and have it answer calls, or if incoming calls are abandoned, the SL2100 disconnects fine.
I tried 81-01-03. The default is 61. I tried higher and lower settings, but it didn't work.
I tried 81-01-22. The default is 40. I tried higher and lower settings, but it didn't work.
There are a lot of 81-01 settings. I'm sure it is in there somewhere.
And, yes, I tried 14-02-18.
I think it is a timing or tone issue, but I don't know what SL2100 setting to change.
In the real world, it is unlikely that I will have a NEC SL2100 behind an Avaya IP Office system, but solving this problem may come in handy for some other type of disconnect problem.