## Inbound messages ```mermaid theme={null} flowchart LR A[Contact sends a WhatsApp message] --> B{Phone number included?} B -- Yes --> C[Match/create contact by phone] B -- No --> D{BSUID already known?} D -- Yes --> E[Match existing contact by BSUID] D -- No --> F[Create new BSUID-only contact] C --> G[Conversation continues normally] E --> G F --> G ``` When an inbound message arrives without a phone number, Treble: 1. Looks up the contact by BSUID. If it already knows this BSUID (from a previous message, or because the phone number was recovered before), the conversation continues exactly as it would for any other contact. 2. If it's the first time seeing this BSUID, Treble creates a new contact anchored to it. The contact behaves normally in your flows, reports, and conversation history — it just won't have a phone number field until one becomes available. 3. If the contact later shares a phone number (see [Recovering a phone number](#recovering-a-phone-number) below), Treble automatically links it to the existing BSUID-anchored contact — no duplicate is created, and the conversation history stays intact. ## Outbound messages Sending a message works the same whether you're targeting a contact by phone number or by BSUID — Treble handles the difference for you automatically. Campaigns, templates, and automations don't need any changes. **Authentication (OTP) templates always require a phone number.** If a contact is BSUID-only and you need to send them an authentication template, you'll need their phone number first — see the next section. ## Recovering a phone number If you have a contact without a phone number and genuinely need it (for example, to send an authentication template, or to sync with a CRM that only matches by phone), Treble supports WhatsApp's **Request Contact Info** button. Add a message with the **Request Contact Info** button to your flow, targeted at the BSUID-only contact. If they agree, WhatsApp shares their phone number back with you — this is always consent-based, the contact has to explicitly agree. The phone number is linked to the existing contact automatically. No manual work, no duplicate contact. This button is still in Meta's private beta and rolling out gradually. Once it's generally available, no changes are needed on your end to start using it.

## HubSpot support Treble's [HubSpot integration](/en/docs/integrations/hubspot/welcome) supports BSUID and username-based contacts out of the box. * Two HubSpot contact properties are created automatically the first time your HubSpot integration syncs: **WhatsApp Business Scope ID** (`whatsapp_business_scope_id`) and **WhatsApp Username** (`whatsapp_username`). * When Treble looks up a contact in HubSpot, it checks phone number first, and falls back to BSUID or username when there's no phone number to search by. * New contacts created from Treble include these fields automatically, the same way `treble_created` and other Treble-managed properties do. * Existing HubSpot contacts get these fields filled in automatically over time as they interact — no manual backfill needed on your side. Unlikely, but if you do, it's not a conflict from our side — Treble only ever *reads* these fields to match contacts, so if you're already populating something useful there, that works in your favor. ### The one real limitation If a contact **already exists in your CRM** because they messaged you before *with* their phone number, and that same person later sends a new message **without** sharing their phone number (username/BSUID only), Treble won't be able to recognize it's the same person — the old contact was never tagged with their username/BSUID, and that's the only information available at that point. In that specific case, a **new, separate contact** gets created in your CRM instead of matching the existing one. This isn't something we can work around — it's a direct consequence of Meta letting users hide their phone number after the fact. It's also a narrow edge case: it only affects contacts who first messaged with a phone number and later hide it, without ever triggering an interaction that would have let Treble tag their existing record first. For CRM integrations other than HubSpot, phone-number-only matching is still the current behavior — we're extending this same BSUID/username support to our other CRM integrations next.

## Frequently asked questions No. Sending, conversations, reporting, and templates all keep working the same way. This is handled transparently by Treble. No, nothing changes about how reporting works for you. Yes — you send to them the same way, Treble resolves the right recipient (phone, BSUID, or username) automatically. They can't be sent until you have a phone number for that contact. Use the [Request Contact Info button](#recovering-a-phone-number) to ask for it, with their consent. No — this is a WhatsApp Business Platform feature that Meta is rolling out. Treble supports it automatically; there's no setting to turn on. No. Your Phone Number ID stays the same, and existing conversations aren't impacted. Yes, if your WABA/number meets Meta's eligibility requirements (verified business, approved display name). This is configured directly in Meta's WhatsApp Manager (**Account tools → Phone numbers → select number → Profile tab → Username**), or via Meta's Username API — Treble doesn't have a UI for reserving it, since it's a Meta-side account setting. Not for your day-to-day use of Treble. The rollout of username *reservation and activation* is happening gradually by country, entirely on Meta's schedule. Regardless of that schedule, Treble's handling of BSUID-only contacts is active everywhere, so you're covered whenever it does reach your market. Check Meta's WhatsApp Manager directly for the current status in a specific country — we can't guarantee it from our side.

## Sources For the full technical details straight from Meta: * [Meta for Developers — Business-Scoped User IDs](https://developers.facebook.com/documentation/business-messaging/whatsapp/business-scoped-user-ids/) ## Next steps See everything Treble syncs with HubSpot. Understand the bigger picture of how Treble works with Meta.