Purchase an Add-On License to Verify Identities by SMS
Where: SMS verification messaging is available in Lightning Experience, Salesforce Classic, and all versions of the Salesforce app. The Identity Verification Credits add-on license is available for purchase for all editions.
Who: You purchase a license for Identity Verification Credits, which allows your org a predetermined number of SMS messages for identity verification. For exact limits, contact your Salesforce account rep.
How: Internal usage for employees doesn’t count toward this limit. However, the Apex method for SMS registration counts.
You can track how many identity verification credits that your org has consumed from the Setup Company Information page. The status of Identity Verification Credits appears under Usage-based Entitlements at the bottom. Typically, the status is updated daily, but can take longer.