SJphone stopped working some months ago on 3x computers. Showing error: 'NAT/Firewall: Blocked'Using Wireshark ISP says: "It shows that the traffic that is having the issues is internal to your network. Please try disabling any firewalls." They have all been disabled.Tried X-Lite and get: Registration error: 503 - No route to host.Could any MS Security Updates have caused the problem?Any suggestions appreciated. 1 person needs an answerI do too

If your NAT/Firewall has blocked it, you should check with vendor.

If by vendor you mean VoIPtalk, I'm also awaiting a reply from them as they providemy VOIP connection.I've also had correspondence with McAfee as I use their prog. They could only suggest my ISP so I'm now going in circles :-(I use a wi-fi phone via my router and that's still ok.

In the end VoIPtalk could not solve the problem except by suggesting X-Lite. Which works ok!