I've had this issue when calling the Thai restaurant down the street. I dial and the line goes dead--no ring, no answer, nothing. The call is evidently connecting, though, because once they called me back after I tried to call them three times unsuccessfully.

I don't make many outbound calls from my home phone, so I haven't noticed a pattern, but I'll keep an eye on things and start reporting call ids to support if I continue to see it happen.

--Jason