http://www.cellreception.com/towers/towers.php?city=los%20angeles&state_abr=ca
You have to scroll to the west on the map to see the Westwood area of L.A.
Based on this hard data, I'm still calling B.S. on the doctor's story.
You're probably right.
However, according to this map (and my experience), I should have a great signal all around Chattanooga. And I do, except for inside the building in which I work (which is right about 1/3 of the way from the top of the map, where all the railroads are)...
http://www.cellreception.com/towers/towers.php?city=chattanooga&state_abr=tn
Now, our building is unique - no windows, and it's blessed with very thick concrete walls. I would think that there were windows on Jackson's house so that even if he had the kind of construction that we have, one could simply go near a window and get reception.
Of course, there's always the slim chance that the nobody had a cell phone. Very slim...