For use in the United States and conforming countries, the telephone number is always in the form:
Format: [NN] [(999)]999-9999[X99999][B99999][C any text]
The optional first two digits are the country code. The optional X portion gives an extension. The optional B portion gives a beeper code. The optional C portion may be used for comments like, After 6:00. While no explicit limit is placed on the text field, receiving systems may be expected to truncate values that are more than 10 characters long. To accommodate the variability of institutional phone systems, the length of the extension and beeper numbers may be extended by local agreement. Examples:
|(415)925-0121X305|
|234-4532CWEEKENDS|