Access to the Customer Matching API and Customer Matching via the Send API is currently available in limited release. To learn more, contact your Facebook partner manager or representative.
Customer Matching allows you to connect existing customers to your bot using their phone number, and optionally their name. You can perform a simple check with the Customer Matching API, or use the Customer Matching functionality in Send API to send a message to the matching user in Messenger.
Customer Matching is in closed beta, only for bots that have a U.S.-based admin for their associated Facebook Page. The phone numbers used to match customers may belong to users in any country.
Customer Matching with the Send API allows you to send a message but instead of sending to a PSID, you specify a user's phone number and optionally their first and last name.
If a matching user is found and they have not previously opted-in to your bot, a message request will be shown to the user inside Messenger. The user can then read the message and decide whether to accept. If the user accepts, you can onboard them to your bot's main experience.