We recently installed Cisco Callmanager for VOIP in our main office. Our VPN employees can call into office and it works fine. But when VPN employees can make connections to other VPN employees or POTS, their is no voice connection on either end. VPNs are routed through a PIX Firewall and all three VPN employees can see the call manager server. Installation company thinks it is something in our firewall. Any ideas?