Glossary
21 terms you will meet in WhatsApp Business infrastructure, in plain words. Each one is defined the way the product actually behaves, not the way the category talks.
B
BSUID business-scoped user ID
A per-business contact identifier Meta is moving to, alongside the raw phone number. Cosend stores both from the first day, with the indexes that let one identity be merged into the other, so the change is a merge rather than a rebuild. The rollout timeline and the exact field names are Meta’s to announce and we do not publish a guess at them.
Business app
The WhatsApp Business app on a phone. Under coexistence it keeps working on the same number the API is attached to, and messages sent from it arrive in the inbox as echoes.
C
Cloud API
Meta’s hosted WhatsApp Business API. Cosend’s Runtime API proxies an allowlisted set of its paths byte-compatibly, so an existing integration moves by changing a hostname.
Coexistence
One number registered to the WhatsApp Business app and to the Cloud API at the same time. An official Meta capability rather than a workaround, and the capability this whole product is built on.
Connection
One WhatsApp number inside one Cosend organization, with its own delivery mode, its own webhook routing and its own throughput ceiling. Plans are counted in connections.
Connection key
An API credential that grants exactly one connection. It is the only credential the Runtime API accepts, because a Graph request names its target in the path — and a key that already names the connection means the path can be checked against it rather than used to look one up.
D
Direct-delivery mode
A per-connection setting in which Cosend verifies the inbound webhook, records metadata only — timestamp, direction, message ID, contact hash, type, status — forwards the full payload to your endpoint and never writes the body. It is free on every plan, and it costs you the inbox, the history import, AI and content-based automation triggers.
E
Echo
A webhook telling you that a message was sent from the phone rather than through the API. It is what keeps the inbox and the app in agreement about one conversation, and it is an event no cloud-API-only provider can emit, because it only exists under coexistence.
Embedded Signup
Meta’s hosted onboarding dialog, and the only sanctioned way to connect a coexistence number. The number is already registered to the app, so the usual registration step is skipped — there is no QR code and no re-registration.
I
Idempotency key
A caller-supplied identifier that makes a retried request safe. Required on every send, because a retried send without one is a duplicate message to a real person. The same key with a different body is refused rather than silently answered with the first result.
M
MCP Model Context Protocol
An open protocol that lets an AI agent call tools. Cosend runs a remote MCP server that exposes one WhatsApp number as tools an agent can call — read the inbox, answer, and author and deploy automations.
Messaging limit
Meta’s cap on how many unique people a business may message outside a customer service window in a rolling 24 hours. It starts low, rises with volume and quality, and it is a property of the business portfolio rather than of one number.
O
Organization key
An API credential that reaches every connection in one organization, with scopes. It works on the REST API and deliberately not on the Runtime API — see connection key for why.
P
Phone number ID
Meta’s identifier for one registered number, and the first segment of most Graph paths. On the Runtime API it is validated against the connection your key already names — the path is never what selects the number.
Q
Quality rating
Meta’s per-number health signal, reported as green, yellow or red, derived from how the people you message respond. Meta does not publish the thresholds that move it between colours, so neither do we; what we do is tell you when it changes, before a template gets paused.
R
Runtime API
Cosend’s Graph-compatible passthrough. Same paths, same payloads, same error envelopes, your version pin forwarded verbatim — with the app secret proof computed for you and every proxied send recorded into the inbox on the way past.
S
Service window the 24-hour window
After a customer messages you, you may reply freely for 24 hours. After that, only an approved template can open the conversation again. A free-form send outside the window is refused rather than delivered.
T
Template
A message format submitted to Meta and approved before use. It is what lets a business start a conversation outside the service window, and its approval status and quality are both things Meta can change without asking you.
W
WABA WhatsApp Business Account
The Meta account that owns your numbers and your templates, and the entity Meta bills directly for messages. It is yours, it stays yours, and Cosend never sits between it and your invoice.
wamid
The identifier of a single WhatsApp message. It is the same value in the app and in the API, which is what makes one conversation out of two clients — key your own records on it.
Webhook override
A per-number callback that takes precedence over the account-level one, so a single number can deliver its events somewhere else. Template and account-level webhooks do not support it and always land on the account callback.