Bring your own account
The platform has no provider account of its own. That one design decision changes who owns the numbers, who holds the quota, and who appears on the invoice.
Read the guide →Two endpoints that look alike and are not
Delivery receipts and inbound replies are different endpoints, configured in different places in your provider’s console. Configure only the receipt URL and opt-out handling stops — silently, with no error anywhere.
One endpoint per direction
Outbound outcomes arrive at the receipt URL. Replies from recipients — including STOP — arrive at the inbound URL. They are separate paths and, in most provider consoles, separate configuration screens under different headings.
This is the single most common way to lose opt-out handling. Receipts keep working, the message log looks healthy, and the suppression list simply never receives any entries. Nothing reports a fault, because from the provider’s point of view nothing is wrong.
| Direction | Path | Configured under |
|---|---|---|
| Outbound outcome | /webhook/sms/{provider} | Delivery receipts / DLR |
| Inbound reply | /webhook/sms/{provider}/inbound | Inbound messages |
What the token proves, and what it does not
The token in the URL identifies which account the event belongs to. It does not prove that the event genuinely came from the provider — per-provider signature verification is not implemented. Treat the inbound endpoint as authenticated by obscurity of the token, and treat provider signatures as something to verify yourself if your risk model needs it.
Not every provider sends STOP to you
- Some providers handle opt-out at the carrier level, in which case no inbound event is produced at all and the platform never sees the reply.
- Where that happens, your own suppression record is a reconciliation tool rather than the only line of defence.
- The provider identifier in the path is case-insensitive, so a differently-cased value is not a configuration bug.
Scope. Inbound handling and suppression are implemented for the SMS channel. Email and WhatsApp do not carry them today.
Keep reading
SMS segments and what you actually pay for
SMS is billed per segment, not per message. Whether your text fits in one segment depends on the character set it needs — and on the encoding you set on the connection.
Read the guide →Opt-out handling
Opt-out is two halves: the suppression record, and the check that runs before a marketing message is handed to the provider. Both run through one shared normalisation, which is the part that usually breaks.
Read the guide →Reading a delivery receipt
A receipt is a sequence of states, not a verdict. Treating an intermediate one as final is the most common way a sending dashboard ends up lying to you.
Read the guide →Pacing, quotas and why we queue
Every connection carries a send rate. The platform queues to that rate instead of firing as fast as a provider will accept, because the fastest way to get throttled is to send at the speed that causes it.
Read the guide →Routing and failover
Routes are ordered by priority and weighted within a connection. The point of the arrangement is that a provider rejecting sends degrades into slower sending, not into silence.
Read the guide →Who decides whether a message is marketing
The platform asks you to declare what kind of message you are sending instead of inferring it from the text. That one field decides whether the opt-out gate applies — and the honesty of the declaration is yours.
Read the guide →A timeout is not a failure
Sending is accepted asynchronously and there is no de-duplication key. Retrying a request you are unsure about sends a second message and bills for it.
Read the guide →Getting a number back
A recipient who opted out can opt back in. The platform deactivates the suppression record rather than deleting it, so the consent trail survives.
Read the guide →What happens when your callback is down
Terminal outcomes are pushed to a URL you control, with a small bounded retry. Your handler has to tolerate a repeat, and it should not expect a call for every message.
Read the guide →Which rate limit you just hit
There are two throttles in front of a send: the one your plan sets, and a much higher one at the network edge. Both answer with the same status code, so the message text is what tells them apart.
Read the guide →Who the recipient actually sees
If you do not name a sender, the platform picks one from the connection that carries the message. Naming one explicitly takes priority everywhere.
Read the guide →What the platform does not keep
Message content is not archived. What is kept is metadata — and among that metadata two fields are load-bearing, because without them a bill could not be reconciled.
Read the guide →