You are correct. Sorry for not making that clear. Node 1 has an Axxess V10. Nodes 2 and 3 have 5200s. VPU on Node 1 supports the voicemail for node 2. What are the factors to determine when the 5000 series PBX should be upgraded to the external controllers? I just want to know the signs so I don't get caught with my pants down.