It could also be Comcast is censoring web services? Time Warrener Cable blocked some websites I wanted to visit from the Coast to Coast website as they said it was too much traffic and thought they were stopping a DoS attack. Cell phone companies a few years back blocked some web apps for the same reason. About eight years ago I bought a cell phone because, every time I tried to call a mobile phone from a pay phone I would get the same exact message you are getting now! Over the years I have tried this many more times and guess since mobile phones are putting pay phones out of business they just refuse to connect the call. Comcast may be doing the same and hoping that you switch to Comcast for you VOIP needs. Just a thought too think about.