"The Phone Company" really meant it, even if you can't keep your doctor .

Note the change from four digits, to seven digits, to a named-exchange, but 4700 is still there. The downtown Hotel Elwell was only open from 1951 to 1965.

DU stood for Dudley, a named telephone exchange from the days of Central TelephoneCo. If you look here http://www.thecentraloffice.com/nv/NVsprint.htm, you can even see the building that housed the Dudley 2 and Dudley 4 exchanges that show up on a lot of old Las Vegas matches.