# Find Sms Auth Phone Number ### Description This runbook searches for which user has a specific phone number registered with SMS Sign-In enabled in Microsoft Entra ID. Unlike regular phone MFA methods, SMS Sign-In numbers must be unique across the tenant. If a number is reserved for SMS Sign-In by one user, assigning it to another user will fail with a "phoneNumberNotUnique" error. Regular phone MFA methods do not enforce uniqueness. This runbook helps administrators identify which user holds a specific SMS Sign-In number for troubleshooting and remediation. ### Location Organization → Security → Find SMS Auth Phone Number **Full Runbook name** rjgit-org\_security\_find-SMS-auth-phone-number ### Permissions #### Application permissions * **Type**: Microsoft Graph * AuditLog.Read.All * User.Read.All * UserAuthenticationMethod.Read.All ### Parameters #### PhoneNumber Phone number to search for in E.164 format (e.g., +492349876543). The number must start with a "+" followed by the country code and subscriber number. | Property | Value | | ------------- | ------ | | Required | true | | Default Value | | | Type | String | [Back to Runbook Reference overview](/automation/runbooks/runbook-references.md) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.realmjoin.com/automation/runbooks/runbook-references/org/security/find-sms-auth-phone-number.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.