we creat vpn tunnel between a draytek router 2600we and DFL700 using IPsec security protocol with des-cbc encryption . this tunnel goes through A watchguard 700x firewall . now data is passing through the tunnel but when we send voice traffic from GNUGK through the tunnel on a voip gateway the signal goes and we hear the bell ring but when pick the phone there is a complete silence on both side can any body tell me what is the problem . thanks usman ali