March 3rd, 2008
Reader: AT&T tells me Time Warner Cable is blocking his VoIP
A reader and information technology professional in the New York area sent me an email this morning that raises the possibility that his high-speed Internet service provider Time Warner Cable 
may be blocking his AT&T CallVantage VoIP service.
Not only does the reader wish to describe his issue, but he would like to hear from others who may be undergoing similar experiences. But first, here’s this reader’s account o what’s been going on:
This past Thursday, TimeWarner did a big upgrade of their service in our area where the network (primarily cable but I’m assuming Internet as well) went down for 3-6 hours. When it came back up, my CallVantage service has stopped working.
After many many hours of talking to both ATT and Time Warner, resetting the TA device, rebooting etc. I still have no phone service. The TA device clearly works - it sees all fo the IP Address info from Time Warner and ATT can see the device on their network. However, I cannot get dial tone.
ATT says the problem is that TimeWarner is blocking certain UDP ports their app needs. They claim they see this problem with TimeWarner Cable frequently. At this point, I am convinced they are right. Have you heard of this yourself? Is this legal? I’ve had no phone service for 4 days. Suppose my business was out of my house?
Anyway, I’m trying to find out if others have seen this kind of behavior by TimeWarner and what there is to do about it.
Russell Shaw is an enterprise computing journalist, analyst and author based in Portland, Oregon. See his full profile and disclosure of his industry affiliations.
