Have a avaya 8500 system that's having trouble. The problem is that they can't conference local calls. They have a PRI with two-way DID trunks for local calls and a T-1 for Long distance. Able to conference LD calls fine but when they try to conf local calls, one of the calls get dropped. We are the provider of the local PRI and do not maintain their switch. They are thinking it's our trouble and we are thinking it's the 8500. What do you guys think? Thanks for any help.