The rest is very accurate, presumably he didn't have a true WEco #500 and found the cheapest #500 set in good shape he could.
AT&T owned 22 operating companies that did local phone service throughout the US, they served at least 2/3-3/4 or all US telephone subscribers. Most major cities were served by Bell, the only major city not was LA which was served by General Telephone(GTE). Automatic-Electric, Kellogg, Stromberg-Carlson, and ITT made #500 set phones were virtually identical to AT&T's Western Electric made phones, they licensed the design out, presumably.
Old AT&T's structure was as follows, AT&T owned 22 local phone companies such as C&P Telephone, Pacific Bell, Illinois Bell, and New York Telephone, these companies were who you paid your local phone bill to and who owned the equipment and building that gave you dial tone. AT&T also owned AT&T Long Lines, the long distance provider which owned major tandem switching machines throughout the US such as 4A Toll Crossbar switches and #1 Crossbar Tandems, they also owned coaxial cables throughout the US and many microwave radio relay stations that operated on L-carrier and microwave carrier respectively. AT&T also owned their equipment supplier, Western Electric, that made everything from undersea cables to 4A Toll machines and your(not technically yours, it was leased) #500 set. AT&T then owned a research laboratory, Bell Labs, that invented many things we still rely on today and many elements of modern technology is based on such as the transistor, UNIX operating system, 4ESS toll office, 4x the capacity of the electro-mechanical 4As.