Random phone number generators, which work the same as other number generators, rely on algorithms that seed random numbers according to software rules. A stable algorithm is essential to ensure that the numbers generated are as random as possible.
In addition to algorithms, random phone number generators also use programming rules to specify desired results. For instance, one programming rule may specify seven- or ten-digit numbers. Another rule may specify the format of the number, area code in parentheses, segments of the number separated by hyphens. As the algorithm seeds numbers, its output is run through one or more filters to generate a list of numbers.
To learn more about how a random number generator works, try using Microsoft Excel’s Rand function to generate a list of random phone numbers. First, open a new spreadsheet, and select cell A:1. Enter =Rand() in the formula bar to generate a random number. Change the cell’s formula to =Rand()*(9999999999-1000000000)+1000000000, and hit Enter. The number in the cell changes to a random ten-digit number. Then copy the formula to a series of cells or a whole worksheet to generate as many numbers as you want. Should you need to format the numbers, use Excel’s Number Format function to customize a format.