WhatsApp Usernames and BSUID: What Changes When the Phone Number Is Hidden

For years a WhatsApp conversation has meant a phone number. Every inbox, CRM and campaign tool assumes it. That assumption is ending: WhatsApp is rolling out usernames, and a customer who adopts one can message a business without showing their number.

For the business the change is small if your tools are ready and confusing if they are not. This guide explains what a username and a BSUID are, what Meta has said about the timeline, which flows can break, and what MonoChat does with these customers.

What changed

WhatsApp users can pick a username. When they message or call a business, the business no longer has to receive the phone number. Instead WhatsApp sends a business-scoped user ID (BSUID), an identifier that is unique to that customer and your business portfolio.

According to Meta’s developer documentation:

• A BSUID is a two-letter country code, a period and up to 128 letters and digits, such as US.13491208655302741918. Use the whole value, including the prefix.
• It is unique to a business portfolio and a user. Another portfolio’s phone number cannot message it.
• It changes if the customer changes their phone number.
• Meta began sharing BSUIDs in webhooks in early 2026, and reserving usernames for businesses opens on June 29, 2026. Usernames roll out gradually through 2026.

Customers do not have to adopt a username, and many will not. Both kinds of customer will reach you for a long time, so your tools need to handle both.

When you will not see the phone number

Meta says the phone number is often omitted from webhooks for customers who adopted a username. It is still included in two cases:

1. You and the customer messaged or called each other from the same business phone number within the last 30 days.
2. The customer is in your contact book, a Meta-hosted feature that stores the phone number and BSUID pairs from your earlier interactions, scoped to your business portfolio.

The BSUID is always included, with or without a username. That is why your system should store it next to the phone number instead of replacing it.

What can break

The risk is in anything that treats the sender as “always a phone number”:

• Inbox and CRM: a new conversation arrives with no number, so it cannot be matched to an existing contact, and a duplicate profile appears.
• Click-to-WhatsApp ads and new inbound chats: these are the first contact, with no earlier interaction to fill the contact book.
• Campaigns: a list built only from phone numbers misses the customer who writes from a username.
• Verification codes: authentication templates, such as one-time passwords, cannot be sent to a BSUID.
• Calls and old numbers: a stored number can be reassigned to someone else, so calling it may reach a stranger.

A checklist for your team

1. Ask your platform. Does it store the BSUID, show customers without a number, and keep the phone and BSUID together on one profile?
2. Keep the phone number. Do not delete numbers you already have. Phone number and BSUID are useful together, and 360dialog also advises keeping both.
3. Use the contact book. Keep Meta’s contact book feature enabled, so that numbers keep coming through for customers you already know.
4. Collect the number when you need it. Ask for it in the chat with a request contact info message, and explain why you need it.
5. Plan OTP flows. Collect the phone number before a flow that sends a verification code.
6. Check consent. Opt-in rules do not change with a username. Read WhatsApp opt-in and keep proof of consent per customer.
7. Test. Meta’s webhook test tool can simulate username scenarios.

How MonoChat handles it

MonoChat handles customers with and without a visible number. What the help center describes:

• In the inbox: when there is no number, the session shows the customer’s @username, or a masked BSUID such as TR.***1111 if there is no username. The raw BSUID is not shown in the session list or the chat header.
• On the customer profile: MonoChat collects every number, BSUID and username it learns from incoming messages, delivery reports, contact cards and WhatsApp notifications, and shows them under CRM › customer › Profile › Customer Channels and in the WhatsApp Identity widget in the chat. Seeing them needs the permission to read customer identities.
• Where a message goes: a flow, a bulk message or an agent writes to a verified phone number first, then to the BSUID.
• Reassigned numbers: when WhatsApp reports that a number now belongs to another account, MonoChat marks it Unverified and stops using it, so a message does not reach the new owner.
• Authentication templates: MonoChat stops the send for a customer with only a username identity and tells you why, because Meta does not allow it.
• Getting the number: send a Contact Info Request message, or a template with a request contact info button. See create a WhatsApp template.

The WhatsApp Identity help article lists every field.

What to do this week

Open your inbox and CRM and look for a conversation with no phone number. If you find one, your setup already receives username customers, and the question is whether your team can see them, match them and answer them. If you find none, run a test with the webhook tool before adoption grows in your market.

MonoChat is business messaging software and an official Meta Business Partner. It connects your own WhatsApp number to Meta’s Cloud API, and you pay Meta for messages directly, with no markup from MonoChat. You can start free at app.monochat.ai.

Sources: Meta for Developers, Business-scoped user IDs; Twilio changelog on usernames and BSUID; 360dialog on usernames.