I'm having a problem making outgoing calls at my office. Every time I make a call and the other side picks up it just goes quiet. Since it's not my office and not my network I can't really ask IT to make any changes, but I suspect it's to do with port blocking or another VoIP service on the same network. I can put my phone through a router and then onto the network. If I were to use a VPN on the router is that possible with the service and is it worth a shot?