if you have VP200 on DMZ and port forwarding for MVP, it will make the incoming calls directly to VP200 instead of going to MVP.
It is best to use both port forwarding to both VP200 and MVP and not use DMZ at all so both calls can work incoming and outgoing calls. Before MVP recent firmware update, I hate it when people called to my VP200, it will re-direct their call to MVP. People will be puzzled why I am on MVP and not on VP200 because the phone numbers are supposed to go to VP200, not to MVP. It will confused lot of people which call to make, VP200 or MVP.
So, it is best to use port forwarding on both MVP and VP200 so people won't get confused anymore. Port forwarding on both VP200 and MVP works beautifully and have no problem so far. Now, I can relax and enjoy calling my friends anytime.