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Meta is introducing WhatsApp usernames. Customers will be able to hide their phone numbers when messaging businesses.

When that happens, you’ll need to use a new identifier called Business-Scoped User IDs (BSUID) instead of phone numbers.

For an easier transition & intercompatibility between BSUIDs and phone numbers, Meta will also launch a feature called the Contact Book. It automatically maps customers’ phone numbers to BSUIDs from conversation events even before username adoption begins, so most of your base is already protected automatically.

The April – June period will be a live testing and adoption window. BSUIDs will be visible in webhooks, Contact Books will be building up mappings, but username adoption won’t start yet. Use this time to understand the change, not to panic-build.

Nothing breaks until username adoption begins in June 2026 and even then, only for net new conversations from users who have adopted usernames.

360Dialog, will provide full specs, examples, and implementation support as the
rollout happens.You won’t have to figure this out alone.

How ALDI Portugal Cut Acquisition Costs by 65% with WhatsApp Contests

If my customer adopts a username, can I still message them?+

Do my clients have to do anything? And do I?+

Which of my messaging flows could break – and when?+

What is a BSUID and why does my system need to handle it?+

The Contact Book is enabled by default – do I need to do anything?+

We use click-to-WhatsApp ads. What changes for us?+

We built our CRM around phone numbers. Where do we start?+

What is the real deadline?+

We manage multiple clients across different portfolios. Will the same customer have a different ID in each one?+

If a customer sets a username key, can I still reach them?+