Dedicated messaging lines for your business
A messaging line is the dedicated, provisioned identity your application sends and receives through — operated by SendiMessage, not shared with any other customer. This is what it is, how you get one, and exactly what it includes.
What is a dedicated messaging line?
A messaging line is a single sending/receiving identity provisioned and operated for one business — never a shared pool split across customers. Every line ships with its own API credentials, its own delivery history, and its own webhook configuration, so activity on one customer's line never mixes with another's.
How a line gets provisioned
You tell us the use case, destination markets, and expected volume on the Request a Line form. Our team reviews it — there is no instant, unattended activation — confirms line requirements and pricing, and provisions the line. You integrate the REST API with the delivered credentials, send test messages to a real recipient on the live line, and then move to production. The same team that provisions the line supports the integration.
What every line includes
A key and secret scoped to your organization, delivered securely and shown once. Every request is authenticated against them.
Messages route over iMessage when the destination and line support it. iMessage delivery is never guaranteed for every recipient or country — it depends on the recipient and what the line supports.
Where fallback is enabled on the line, traffic that can't deliver over iMessage goes out as SMS automatically, on the same request.
On lines with incoming messaging turned on, customer replies are threaded into conversations and delivered to your endpoint as signed webhooks.
Every message carries a status history — queued, sent, delivered, or error — readable over the API and pushed to your webhook endpoint.
Signed receive and outbound events, so your systems react to activity on the line without polling.
Can a business have more than one line?
Yes. Businesses commonly provision one line per market, brand, department, or workflow (support vs. sales vs. transactional, for example) — each with its own credentials and its own delivery history, reviewed and provisioned the same way.
The Apple reality
Apple does not offer a public server-side iMessage API for sending business messages from your application, and does not partner with or endorse third-party providers for this. SendiMessage is an independent product that operates managed messaging lines and exposes them through one REST API — iMessage where the recipient and line support it, with SMS fallback where configured.
Send through the line
curl -X POST "https://api.sendimessage.com/v1/send-message" \-H "Content-Type: application/json" \-H "X-API-Key: $SENDIMESSAGE_API_KEY" \-H "X-API-Secret: $SENDIMESSAGE_API_SECRET" \-d '{ "number": "+14155550123", "content": "Your order shipped." }'
line_handle targets a specific line when you have more than one; omit it to use any active line.
FAQ
Is activation instant?
No. A line is reviewed before it's provisioned, and provisioning is handled by our team — there is no self-serve signup or unattended instant activation.
Do lines share a number pool with other customers?
No. Every line is dedicated to one business. Nothing about sending, delivery, or history is shared across customers.
Does every line get iMessage delivery for every recipient?
No. iMessage delivery depends on the destination and what the line supports — it's never guaranteed for every recipient or country. Where SMS fallback is configured, undeliverable iMessage traffic goes out as SMS instead.
Is SendiMessage affiliated with Apple?
No. Apple does not offer a public iMessage API and does not partner with or endorse third-party providers, including SendiMessage. We operate independent managed messaging infrastructure.
How is a line priced?
Per active line, billed monthly — see the pricing page for current figures and what's included.
Provision your first line
Tell us about your use case and we'll review, provision, and guide the integration.