What Is WhatsApp BSUID? Usernames, Business-Scoped User IDs & Everything Changing in 2026

WhatsApp is introducing usernames and Business-Scoped User IDs (BSUIDs) in 2026. Users can set a username (like @yourname) to hide their phone number from businesses. Businesses will receive a unique BSUID for each customer instead. BSUIDs start appearing in webhooks on March 31, 2026, and become usable for sending messages in May 2026.

What Is a WhatsApp Username?

A WhatsApp username is an optional, unique handle (like @sarah_designs) that any WhatsApp user can set. Once enabled, businesses see the username instead of the user's phone number. Usernames follow the same format as Instagram handles and are launching later in 2026.

Think of it like picking a display name for a game — except this one protects your phone number from every business you message on WhatsApp.

• Completely optional. Nobody is forced to set one. If you skip it, everything works exactly as it does today.
• One per person. You can only have one username at a time, but you can change it periodically.
• Doesn't break anything. Changing your username doesn't affect your phone number, BSUID, or conversation history.

What Are the Format Rules for WhatsApp Usernames?

WhatsApp usernames must be 3–35 characters long, contain only English letters (a–z), numbers (0–9), periods (.), and underscores (_), include at least one letter, and cannot start/end with a period, contain consecutive periods, start with "www," or end with a domain extension like .com.

One important detail: capitalization doesn't matter (MyName and myname are the same), but periods and underscores do (my.name and my_name are different usernames).

What Is a WhatsApp BSUID (Business-Scoped User ID)?

A BSUID (Business-Scoped User ID) is a unique identifier that WhatsApp automatically generates for every user–business pair. It looks like US.13491208655302741918 — a country code prefix followed by up to 128 alphanumeric characters. BSUIDs replace phone numbers as the primary way businesses identify WhatsApp users who enable usernames.

Here's the key concept: if you message three different businesses on WhatsApp, each business gets a different BSUID for you. Business A cannot use their BSUID to figure out that you also talk to Business B. Your identity stays compartmentalized.

How Does the BSUID Format Work?

A BSUID like US.13491208655302741918 has three parts:

• US — The user's ISO 3166 alpha-2 country code (US for United States, IN for India, BR for Brazil)
• . (period) — A separator
• 13491208655302741918 — Up to 128 alphanumeric characters, unique to this user–business portfolio pair

WhatsApp BSUID vs Phone Number: Key Differences

Here's how a BSUID compares to a traditional phone number:

• Format: Phone number looks like +1 6505551234. BSUID looks like US.13491208655302741918.
• Uniqueness: A phone number is the same across all businesses. A BSUID is different for each business portfolio.
• Privacy: A phone number exposes the user's real identity. A BSUID only reveals a scoped code.
• Cross-business tracking: Possible with phone numbers. Not possible with BSUIDs.
• Sending messages: Phone numbers work today. BSUIDs work from May 2026.
• Auth templates: Phone numbers work for all types. BSUIDs cannot be used for one-tap, zero-tap, or copy code authentication templates.

Key Properties of WhatsApp BSUIDs

• Auto-generated — no action needed from users or businesses.
• Scoped per business portfolio — each portfolio gets a unique BSUID for each user.
• Changes when the user changes their phone number — the business receives a notification webhook.
• Must be used in full — country code, period, and all characters. Omitting or modifying any part causes API requests to fail.
• Doesn't work for all message types — one-tap, zero-tap, and copy code authentication templates still require phone numbers.

What Is a WhatsApp Parent BSUID?

A parent BSUID is an additional cross-portfolio identifier for companies with multiple linked business portfolios. It looks like US.ENT.11815799212886844830 (note the ENT prefix) and works across all linked portfolios, solving the problem of different BSUIDs per portfolio for the same customer.

To enable parent BSUIDs, you must contact your Meta point of contact and check eligibility. Once your portfolios are linked, parent BSUIDs automatically appear in webhooks via a new parent_user_id field.

Key difference: A regular BSUID is scoped to one portfolio. A parent BSUID (format: US.ENT.xxxxx) works across all linked portfolios. Parent BSUIDs require Meta approval and are designed for companies managing multiple business portfolios.

WhatsApp BSUID and Usernames: Key Dates and Timeline

• March 31, 2026 — BSUIDs start appearing in production webhooks. Webhooks now include the user_id field.
• Early April 2026 — Contact book feature launches (Meta-hosted). Automatically stores user phone numbers and BSUIDs.
• Early May 2026 — REQUEST_CONTACT_INFO button available. Businesses can ask users to share their phone numbers.
• May 2026 — APIs support sending messages using BSUIDs. You can message users without knowing their phone number.
• Later in 2026 — Usernames go live for all WhatsApp users. Users can hide phone numbers from businesses.

What Is the WhatsApp Contact Book Feature?

The WhatsApp contact book is a Meta-hosted feature launching in early April 2026 that automatically stores user phone numbers and BSUIDs whenever a business and user interact. It requires no integration work and is scoped to the business portfolio level.

• No setup needed — Meta hosts and manages it automatically.
• Forward-looking only — only interactions after launch are captured. No retroactive data.
• Portfolio-scoped — any interaction between any of your business phone numbers and a user stores their info for the whole portfolio.
• Can be disabled anytime — in Meta Business Suite. Disabling deletes all stored data permanently.

How to Request a User's Phone Number on WhatsApp

Starting in early May 2026, businesses can add a REQUEST_CONTACT_INFO button to utility and marketing message templates. When a user taps this button, their phone number and virtual contact card (vCard) are shared with the business via a contacts webhook.

The button can't be customized — it's a standard WhatsApp element. Not every user will tap it, so design your flows to work with or without a phone number.

What Are WhatsApp Business Usernames?

WhatsApp Business usernames are optional, unique handles that businesses can adopt. Unlike user usernames, business usernames do NOT hide the business's phone number. They make businesses searchable by exact username on WhatsApp — something display names don't support.

How Does WhatsApp BSUID Change the Business API?

The WhatsApp Business API now supports two addressing fields: "to" (phone number) and "recipient" (BSUID or parent BSUID). All webhook types include new user_id, parent_user_id, and username fields, while phone number fields like wa_id may be omitted for username-enabled users.

How Gallabox Helps You Navigate WhatsApp's BSUID Transition

The WhatsApp username and BSUID rollout is one of the most significant changes to the WhatsApp Business Platform in years. At Gallabox, we're building native BSUID support directly into our platform — seamless transition for your team, unified customer profiles, and built-in phone number request flows.