SMS

Send SMS with the same API key and SDK you use for email. Retransmit detects the destination country and routes the message to an available provider.

Send a message

import { Retransmit } from "retransmit.dev";
 
const retransmit = new Retransmit(process.env.RETRANSMIT_API_KEY);
 
const { data, error } = await retransmit.sms.send({
  from: "Acme",
  to: "+237670000000",
  text: "Your order is ready for pickup.",
});

Recipients must be in international E.164 format, such as +237670000000. One request takes up to 50 recipients, all in the same country.

Sender IDs

from is the name that appears on the recipient’s handset instead of a phone number. Request it in the dashboard under SMS > Sender IDs, and pass it as from once it is approved.

A request asks for three things:

• The name. 3 to 11 letters, digits, spaces, hyphens, or underscores.
• The countries you send to. Approval is per country.
• The region. Where the name is registered. Pick the one closest to your recipients; it cannot be changed afterwards.

In most countries that is the whole form: the carriers there take the name as it is. The country picker says which kind each destination is, No registration needed or Carrier registration required. Picking one of the second kind adds three questions, because they go on the filing the carriers read:

• What you send.
• A sample message. Registrations are rejected when the sample does not match the traffic.
• The legal entity behind the name, and its website if it has one.

Those three are required only while a registration country is selected. Retransmit asks for nothing its providers do not, so a request that only targets countries with no registration needs nothing but the name and the destinations.

Approval follows the same split. Where no registration is involved, it is ours to give and is usually same-day. Where a carrier files it, it takes a few days and the request sits pending until the carriers clear it.

You do not need an AWS or carrier account. Retransmit holds the provider relationships, so one API key still covers every channel.

Once approved, pass the name as from:

const { data, error } = await retransmit.sms.send({
  from: "Acme",
  to: "+237670000000",
  text: "Your order is ready for pickup.",
});

Rules:

• A sender ID approved for one country does not work in another. Request each country you send to.
• Messages carrying a sender ID go out of the region it was registered in. You do not pass the region on a send; the name carries it.
• Sending with a name you have not had approved returns 422 sender_not_allowed.
• Omit from and Retransmit uses your approved sender for that country. If you have none, the message goes out under a shared default, which some carriers filter.

The United States, Canada, and Mexico do not accept alphanumeric sender IDs at all. Those destinations need a number, which Retransmit does not offer yet.

Routing and availability

Retransmit reads the destination country from the recipient number and picks the cheapest provider that covers it. Direct carrier integrations (MTN and Orange in Cameroon) come first where they exist; AWS End User Messaging is the global fallback for every other destination. If no provider covers that country, the request returns 422 no_route and nothing is queued.

For mixed-country recipient lists, send one request per country.

Choosing a provider

You do not have to guess which carrier fits a number. Leave provider out and Retransmit routes the message for you.

Pass it when you need one specific carrier, for example because your sender ID is registered there or a customer’s number is on that network. sns is the one that reaches every destination, so it is the safe value to pin:

const { data, error } = await retransmit.sms.send({
  to: "+237670000000",
  text: "Your order is ready for pickup.",
  provider: "sns",
});

The value is the carrier, not one of its country operations, so a request keeps working as we add more countries for that carrier. A pinned send never falls back to another provider: if that carrier cannot deliver to the destination, the request returns 422 no_route.

The route a message actually took is returned as provider on Get SMS. That field is more specific than what you send, naming the country operation: mtn_cm, orange_cm or aws_sns. What you asked for comes back as requested_provider.

Message segments

SMS is billed per segment, not per request. The send response includes segments, the number of billable GSM-7 or UCS-2 parts. Unicode characters reduce how many characters fit in each segment.

{
  "id": "sms_xxxxxxxxxxxx",
  "status": "queued",
  "country": "CM",
  "segments": 1,
  "created_at": "2026-09-01T12:00:00.000Z"
}

What a message costs

SMS is pay as you go on every plan: there is no included volume, and a payment method  is required before the first send. Without one a send fails with 402 quota_exceeded.

The rate is per segment and per recipient, and depends on the destination country — carrier costs differ by more than a hundredfold between the cheapest and dearest destinations, so a single rate would be meaningless. A three-segment message to ten recipients bills thirty segments at that country’s rate.

Which carrier Retransmit routes through never changes what you pay. Routing picks the cheapest carrier covering the destination; the rate is fixed per country, so the same message costs the same whichever route it takes.

Usage appears on your monthly invoice as a single SMS line, and the running total for the period is on the billing page .

Track delivery

Poll retransmit.sms.get(id) or GET /v1/sms/:id for the current status and event history. For push updates, subscribe to sms.sent, sms.delivered, sms.undelivered, and sms.failed webhooks.

See Send SMS for the full request contract.