What are my options for a NON-VIOP business phone system? VOIP is not an option. Please help me out!?

I'm trying to upgrade my companies current phone system. We currently use an Avaya phone system, and Verizon as our service provider. What we're looking to do is upgrade our conference capabilities. Right now we can only have two external parties connected unless we use a dial in number. Although the dial in number works my boss would prefer for us to be able to simply call people and add them to the call as needed, as well as let them call in when needed. In addition he would like to be able to transfer the call to a another phone if need be. For many reasons a VOIP system has been ruled out and is not an a option (although it seems like an easy solution, trust me I've been pushing for it). There has to be a non-VOIP phone system out there that can handle these simple tasks. Please help!