BBC America is not the real BBC World News. BBC America carries some of the latter, but only once in awhile. Most of the time you get entertainment only. The BBC on I805 is radio only if I recall correctly.
There used to be a feed on one of PBS's AMC-21 (125W) SD channels that carried BBC World News a few times per day, at least during the week. That's the only FTA version that has been readily available in the recent past.
If you want BBC World News 24/7, you can always subscribe to Shaw Direct, which can be easily received down to Mexico. The picture quality on most of the Shaw channels is considerably better than what Dish Network and DirecTV offer for the equivalent channels, and for reasons obvious to some, approaches master feed quality.