When you enter phone numbers in standard Phone fields in Salesforce CRM, Salesforce preserves whichever phone number format you enter. Phone fields can accept a maximum of 40 digits in length when entered via the Salesforce UI. This 40-digit limit does not apply to phone numbers entered via the API.
For full guidelines, please review the Formats for Currency, Dates, Times, Names, and Phone Numbers documentation.
Salesforce CRM applies special formatting logic to standard Phone fields. There are exceptions to the automatic formatting behavior when the User Locale is set to English (United States) or English (Canada).
If your User Locale is set to "English (United States)" or "English (Canada)," Salesforce formats 10-digit and 11-digit phone numbers starting with "1" as described below. Phone numbers with 9 digits receive no automatic formatting.
Data is saved as entered, without any formatting. For example, the 9-digit number 123456789 is saved as 123456789.
Phone numbers beginning with 1: For 10-digit numbers, data is saved using parenthesis formatting. For example, the number 1234567890 is automatically saved as (123) 456-7890. For 11-digit numbers beginning with 1, the leading "1" is dropped and the data is saved as a 10-digit number. For example, the number 12345678901 is saved as (234) 567-8901.
Phone numbers beginning with any other digit: For 10-digit numbers, data is saved using parenthesis formatting. For example, the number 2345678901 is saved as (234) 567-8901. For 11-digit numbers beginning with any digit other than 1, no automatic formatting is applied. For example, the number 23456789012 is saved as 23456789012.
Note: If you do not want the parentheses-space-hyphen formatting for a 10 or 11-digit number, enter a "+" before the number. For example, entering +49 1234 56 78-0 preserves the number in that exact format.
Phone numbers that contain a hyphen behave differently in Salesforce Classic and Lightning Experience. In Lightning Experience, a number entered as 234-567-8901 is saved exactly as entered. In Salesforce Classic, the same number 234-567-8901 is automatically reformatted to (234) 567-8901.
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