We are using DMVPN at 4000 sites currently and it is working extremely well. We have not done any real-time on DMVPN, only interactive data. Another business unit is deploying VoIP phones, however largely untested. Depending on your implementation, I would use a test center and measure jitter and latency first, spoke to spoke routing (phase 3) multicast routing and SIP control channels, in that order. I have not heard anything that would lead me to believe it would not work. We recently had scalability issues with PSK rotation for security compliance, I would recommend PKI for a large implementation. Best of luck, Brian
