Thanks, Kent Clark, for providing those details. I’m reasonably confident that none of the theories put forth so far have to do with the real problem, but I don’t pretend to have a strong explanation, either.
Here’s what I think we can rule out and why:
I agree with one poster that your phone didn’t suck bandwidth from your TV, but for a different reason than the one drachillix mentioned. I also think it’s unlikely that there was any sort of RF interference that caused your TV signal to go away, also for technical reasons (see below).
While drachillix’ post is on-target for IP networking, it’s not applicable to most cable providers–the vast majority of those in the US use quadrature amplitude modulation (QAM) over coaxial cable to customers’ modems and set-top boxes. In the context of QAM, your data connection has its own dedicated channels; it doesn’t compete with the television portion of your cable signal. They’re literally on different channels.
Scabpicker is totally right that AT&T’s U-Verse service can see data and TV interfere with each other. U-Verse is IPTV (television over internet protocol) and while quality-of-service controls should prevent data use from killing a TV signal, I totally believe that AT&T misconfigured something and inadvertently choked off the TV’s allocated IP bandwidth.
I’m an IP networking guy and a mechanical engineer, but what follows is really the domain of electrical engineers…I welcome any input and corrections from those who know these things better than I do:
[li]Each QAM channel is 6 MHz wide and has a theoretical data rate of about 38 megabits per second. That bandwidth can be used for either internet data or regular television channels.[/li][li]One QAM channel can carry up to a dozen standard-def television channels. If you’re paying for, say, 150 Mb/s internet speeds, you’ll typically have a DOCSIS 3.0 modem, which supports bonding a number of QAM channels together for both upstream and downstream data.[/li][/ul]
Regarding RF interference, coaxial cable consists of an inner wire, a dielectric insulating layer and an outer conductive shielding layer. (The shielding is covered with another polymer insulating layer as well). That outer conductive layer is called “shielding” because it effectively shields the inner wire from RF interference. I guess it’s possible to have a wiring issue that prevents the shielding from doing its job, but that seems really unlikely to me.
Like I said, I don’t have an utterly compelling explanation for you, but I can come up with a few plausible ones:
[li]“Bad wiring” sounds like a cop-out, but intermittent shorts can cause weird behavior.[/li][li]It’s possible that your cable company has some bad hardware upstream from you that was affected by the flood of data you say your phone induced.[/li][li]It was a coincidence. You described the disturbance happening over about four seconds. That’s about how long it would take for a cable tech to disconnect the wrong thing, realize that he or she made a mistake, and plug it back in. Or it could have been any of a number of coincidental disturbances. Human beings are wired to perceive causal connections between simultaneous events, and we can’t discount the hoary admonition that correlation is not causation.[/li][/ul]
I hope this helps. Unless this sort of thing starts happening regularly, it may be impossible to find a definitive cause.