On the User object in Salesforce, there is a standard field called Mobile. This field displays on User records and on the user's Chatter profile. Salesforce automatically formats a 10-digit phone number as (###) ###-####, and an 11-digit number as +1 ##########.
When specific users update their Mobile phone number to a 10-digit format and save, the number may revert overnight to the +1 ########## format — even though only 10 digits were entered. The Last Modified By field on the User record will appear to show the change was made by the user themselves.
This article explains why the Mobile phone field on a User record reverts to the +1 format overnight, and how to prevent it using a Validation Rule. The behavior is caused by SMS Identity Confirmation, a feature that cannot be disabled once enabled.
Root Cause: The reversion is caused by a feature called SMS Identity Confirmation, located at: Setup > Security Controls > Session Settings > Enable the SMS method of identity verification. This feature cannot be disabled once enabled. When the phone number reverts, it counts as a record edit, meaning Validation Rules apply.
NOT(CONTAINS(MobilePhone,"-"))NOT(CONTAINS(MobilePhone,"-"))This validation rule ensures that any Mobile number contains a hyphen, preventing the incorrect format from being saved.
000382646

We use three kinds of cookies on our websites: required, functional, and advertising. You can choose whether functional and advertising cookies apply. Click on the different cookie categories to find out more about each category and to change the default settings.
Privacy Statement
Required cookies are necessary for basic website functionality. Some examples include: session cookies needed to transmit the website, authentication cookies, and security cookies.
Functional cookies enhance functions, performance, and services on the website. Some examples include: cookies used to analyze site traffic, cookies used for market research, and cookies used to display advertising that is not directed to a particular individual.
Advertising cookies track activity across websites in order to understand a viewer’s interests, and direct them specific marketing. Some examples include: cookies used for remarketing, or interest-based advertising.