WhatsApp is changing how it identifies users: instead of relying mainly on the phone number, it is moving to a more stable identifier — the WhatsApp BSUID (Business-scoped user ID). MAAC and CAAC already support it, so your existing marketing and customer-service workflows are not affected.
This article explains what the WhatsApp BSUID is, how it affects user identification and your existing customers, and what MAAC and CAAC currently support.
This update does not affect your existing WhatsApp contacts or messaging, and there is nothing you need to set up. It is a change on Meta's platform side (not a MAAC / CAAC feature change), so that "new users who hide their phone number" can still be correctly identified, segmented, and messaged in the future.
What is the WhatsApp BSUID?
WhatsApp has introduced a Username feature: users can choose to chat with businesses using a username (for example @A.Whitman) instead of revealing their phone number. To ensure businesses can still recognize a user after their phone number is hidden, Meta is introducing the WhatsApp BSUID at the same time.
Conceptually, the WhatsApp BSUID is similar to a LINE friend ID: Meta generates a dedicated identifier for each "user × business" pair. In other words, the same user has a different BSUID under each brand (business).
- Purpose: a stable and anonymous identifier for a WhatsApp user. Even if the user chooses to hide their phone number, you can still recognize the same user through the BSUID.
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Format:
{two-letter country code}.{up to 128 alphanumeric characters}, for exampleSG.2062694890952618. It is clearly different from a phone number (such as+886912345678). - Scope: each BSUID is valid only within that business and cannot be shared across brands.
Impact on user identification and existing customers
Existing customers and previously engaged users: not affected
If a user has not enabled a Username, their phone number is provided just as before — exactly the same as today.
As long as you already have the user's phone number, or you have recently exchanged messages with the user (whether you sent, or the user messaged you), your identification and messaging flows stay the same — you can still recognize and message them by phone number as before.
For these existing contacts, the system automatically adds the BSUID in the background while keeping the original phone number. In general, no duplicate contacts are created, and you do not need to do anything.
Users who have exchanged messages with you are kept in your business contact list (Contact Book — the list of WhatsApp contacts you have accumulated). For a period after the last interaction (about 30 days), even if the user has turned on phone-number hiding, the data you receive will still include the phone number, so existing customers are not affected during the transition.
Maintaining regular interaction with your users helps you keep obtaining and updating their phone numbers, reducing the cases where a user can only be identified by BSUID in the future.
Brand-new users who hide their phone: identified by BSUID
When a brand-new user who has never interacted with you has phone-number hiding turned on at their very first contact, you will only receive that user's WhatsApp BSUID, not the phone number. In this case the system identifies the contact by the BSUID, and the contact's identifier field shows the BSUID value (instead of a phone number).
Authentication messages (such as login verification codes and one-time passwords (OTP), including one-tap, zero-tap, and copy-code formats) still require a phone number and cannot be sent with a BSUID alone. If your flow uses these messages, please make sure you have obtained the user's phone number first.
WhatsApp BSUID support across the five MAAC modules
MAAC has completed WhatsApp BSUID adaptation. The following five modules all handle WhatsApp contacts identified by BSUID correctly:
| Module | Support details |
|---|---|
| Contact | WhatsApp contacts identified by BSUID can be created and displayed normally. In 【Unified Contact】 → 【Channel contacts】, the contact's channel ID (the identifying data used to recognize this WhatsApp contact) shows the BSUID value. |
| Segment | Segments built with 【filter conditions】 or a 【specified contact list】 cover BSUID contacts normally. 📌 Exception: 【Create a segment by importing WhatsApp Mobile】 is the exception — see the FAQ below. |
| Broadcast | You can broadcast WhatsApp messages to BSUID contacts normally. |
| Auto Reply | Messages from BSUID contacts trigger and receive auto replies normally. |
| Journey | BSUID contacts can enter journeys and receive journey messages normally. |
CAAC displays the WhatsApp BSUID for contacts
In CAAC, the identifier of a WhatsApp contact shows the BSUID value directly, helping agents recognize users who are "identified only by BSUID, with no phone number." The customer-service flow and conversation continuity stay the same and are not affected.
FAQ
Why do some WhatsApp contacts show an alphanumeric string as their identifier instead of a phone number?
Because that user has turned on phone-number hiding, so what you receive is their WhatsApp BSUID (for example SG.2062694890952618). This is normal — it means the system is identifying this contact by BSUID; you can still broadcast, run journeys, and so on for them.
Does this update require me to set anything up?
No. MAAC and CAAC have completed support automatically, and your existing WhatsApp contacts and messaging flows are not affected.
Why would a user hide their phone number? Is it the default?
It is not the default. This is a privacy option WhatsApp offers to users, which they turn on themselves. Most existing customers will still have a phone number; the main impact is on "brand-new users who choose to hide their phone."
Can I still send WhatsApp messages using a phone number?
Yes. As long as you already have the user's phone number, you can still send messages normally. The phone number can still be used for sending; it is simply no longer the sole, stable basis for identification.
For a contact who only has a BSUID, can I message them proactively?
Yes. You can still send WhatsApp messages to BSUID-only contacts through Broadcast, Journey, and so on (subject to WhatsApp's opt-in and message-category rules). The only exception is authentication messages, which still require a phone number — see the "Authentication message templates" note above.
Will the same user have the same BSUID under my brand and other brands?
No. A BSUID is a dedicated identifier for the "user × business" pair. The same user has a different BSUID for different businesses, and it cannot be mapped across brands.
Will the same WhatsApp user be merged into a single Unified Contact across MAAC and CAAC?
If you have enabled Customer Data Hub (CDH), the system uses the WhatsApp BSUID as one of its merge keys to combine the same user’s contact data from MAAC and CAAC into a single 【Unified Contact】. As a result, even when a user is identified only by a BSUID (with no phone number), they can still be matched to the same customer across MAAC and CAAC. If CDH is not enabled, the contacts in each channel remain separate.
If a user changes their phone number, will the BSUID change?
When a user changes their phone number, Meta may generate a new BSUID for them. (If the user only changes their username, the BSUID does not change.)
I sync my WhatsApp contact data back to my own CRM or another system — what should I watch out for?
We recommend storing a dedicated BSUID field in your CRM / system (alongside the phone number and email) as a stable basis for identification. This way, even if a user hides their phone number in the future, you can still map them to the same customer via the BSUID, avoiding broken interaction history caused by an identifier change.
Why can't I find some WhatsApp contacts when using 【Create a segment by importing WhatsApp Mobile】?
Because 【Create a segment by importing WhatsApp Mobile】 matches the list by phone number, and contacts identified only by BSUID have no phone number to match against, so they are not included. To cover these contacts, please build the segment using 【filter conditions】 or a 【specified contact list】 instead.