Contacts & BSUID Mapping

What Are BSUIDs?

A BSUID (Business System User ID), also referred to as wa_id, is the identifier Meta uses internally for a WhatsApp user. To send messages via Cloud API, you must first resolve a phone number to its BSUID using Meta's /contacts endpoint. Dualhook provides this lookup directly from the dashboard.

Quick Paste

Enter one or more phone numbers in international format and resolve them instantly. Dualhook calls Meta's /contacts endpoint and returns the corresponding wa_id for each number. If a number is not registered on WhatsApp, Dualhook indicates this clearly in the results.

CSV Upload

For bulk lookups, upload a CSV file containing phone numbers. Dualhook processes the file, resolves each number, and returns the results. This is useful when onboarding a large contact list to Cloud API messaging.

Passive Discovery

When Dualhook receives smb_app_state_sync webhook events from Meta, it can passively discover BSUID mappings without requiring an explicit lookup. These mappings are surfaced in the dashboard alongside manually resolved contacts.

Why BSUIDs Matter

Cloud API requires a wa_id to send messages. Without resolving a phone number first, the send request will fail. Dualhook makes this prerequisite step accessible from a single interface instead of requiring direct API calls.