One of the earliest telephone directories found online for Alvarado and Decoto is from 1916. This directory is part of the directory published for "Oakland, Alameda, Berkeley and Counties of Alameda, Contra Costa, Marin, San Mateo, and Palo Alto Exchange." It was published by the Pacific Telephone & Telegraph Company in February 1, 1916.
The directory published for Alvarado had a total of 27 numbers. The exchange was run by F. C. Harvey out of his store on Smith Street (now Bronco Billy's). Most of the key merchants in Alvarado had a phone, including the Bank of Alameda County, two salt companies, Riverside Hotel, Hellwig meat market, Matsumoto Japanese store, Alvarado lumber yard, Alvarado laundry, the postmaster and train station. A number of key residents also had phones at their homes, like F. B. Granger, Fred Harvey, George Hellwig, F. Weigman, William McCoy and others.
Fourteen of the 27 phone numbers had a letter listed after the number. This indicated that the phone line was a party line. Emery, Granger, Wiegman, and the Riverside Hotel were at phone number 3, but Emery was 3W, Granger was 3R, Wiegman was 3M, and the hotel was 3J. The phone would ring different times for each of the parties on the line. Party lines kept the cost of telephone service down.
The 1916 listing for Decoto only lists 7 phone numbers. The exchange was run by John L. Olson, out of his store at the corner of 10th and I streets (now the Supermercado Guadalajara). Only businesses were listed, including James Hanley, the local doctor. Other businesses were Centerville Garage at the corner of Decoto and Niles Rd (Mission Blvd), Essex Lumber Company, Salz Warehouse, and both the Western Pacific and Southern Pacific railroad depots. None of the lines were party lines.