You can try tone check disconnect in 400 but i've had little success with it. It's supposed to listen for dial tone or re-order tone and treat it as a disconnect signal.
We have this problem out here with TW and some carriers out in the middle of nowhere, best bet is to complain to them until they fix the problem which in the rural cases meaning upgrade the switch to one that supports disconnect supervision.
If you want you can look into the viking CPC product line that will send you the disconnect the system is looking for but they are pricey.

Last edited by Genesiscomm; 08/05/14 02:10 PM.