One of my locations has a 2821 MGCP gateway with loopstart FXO trunks. Incomming calls are plar to AA in the CUE. My problem is if the inbound caller hangs up before speaking to a live person (listening to the AA), the FXO port on my gateway will stay connected for 30-40 seconds. I've tried different solutions recommended in this link but have not been able to fix this problem.
What else can I try?