3.28 Sampling telephone area codes. There are approximately 341 active telephone area codes covering Canada, the United States, and some Caribbean areas. (More are created regularly.) You want to choose an SR5 of 25 of these area codes for a study of available telephone numbers. Label the codes 001 to 341 and use the Simple Random Sample applet or other software to choose your sample. (if you use Table B, start at line 129 and choose only the first 5 codes in the sample.)