Libraries & SDKs

The API is a clean REST + JSON interface, so it works from any language with an HTTP client — no SDK required. Every endpoint page in these docs includes ready-to-paste examples in eight languages:

Language	HTTP client used in examples
cURL	—
Node.js	Built-in fetch (Node 18+)
Python	requests
PHP	curl extension
Ruby	net/http (stdlib)
Java	java.net.http.HttpClient (Java 11+)
Go	net/http (stdlib)
.NET	HttpClient (C#)

Pick your language once in any code block — the choice follows you across the entire site.

The full loop in your language

Send a message:

cURL

curl -X POST https://restlink23telecom.com/api/v1/sms/send \
  -H "X-API-Key: $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "to": [
    "+14155551234"
  ],
  "message": "Your verification code is 847291",
  "sender_id": "MyApp"
}'

Node.js

const res = await fetch('https://restlink23telecom.com/api/v1/sms/send', {
  method: 'POST',
  headers: { 'X-API-Key': process.env.API_KEY, 'Content-Type': 'application/json' },
  body: JSON.stringify({
    "to": [
      "+14155551234"
    ],
    "message": "Your verification code is 847291",
    "sender_id": "MyApp"
  }),
});

if (!res.ok) {
  const err = await res.json();
  throw new Error(`${err.error_code}: ${err.description}`);
}
const data = await res.json();
console.log(data);

Python

import os
import requests

res = requests.post(
    "https://restlink23telecom.com/api/v1/sms/send",
    headers={"X-API-Key": os.environ["API_KEY"]},
    json={
        "to": ["+14155551234"],
        "message": "Your verification code is 847291",
        "sender_id": "MyApp"
    },
)
res.raise_for_status()
print(res.json())

PHP

<?php
$ch = curl_init('https://restlink23telecom.com/api/v1/sms/send');
curl_setopt_array($ch, [
    CURLOPT_CUSTOMREQUEST  => 'POST',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER     => ['X-API-Key: ' . getenv('API_KEY'), 'Content-Type: application/json'],
    CURLOPT_POSTFIELDS     => json_encode([
        'to' => ['+14155551234'],
        'message' => 'Your verification code is 847291',
        'sender_id' => 'MyApp'
    ]),
]);

$response = curl_exec($ch);
$status   = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

if ($status !== 200) {
    throw new Exception("HTTP $status: $response");
}
$data = json_decode($response, true);
print_r($data);

Ruby

require "net/http"
require "json"

uri = URI("https://restlink23telecom.com/api/v1/sms/send")
req = Net::HTTP::Post.new(uri)
req["X-API-Key"] = ENV.fetch("API_KEY")
req["Content-Type"] = "application/json"
req.body = {
  to: ["+14155551234"],
  message: "Your verification code is 847291",
  sender_id: "MyApp"
}.to_json

res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |http| http.request(req) }
raise "HTTP #{res.code}: #{res.body}" unless res.is_a?(Net::HTTPSuccess)

puts JSON.parse(res.body)

Java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

HttpClient client = HttpClient.newHttpClient();

HttpRequest request = HttpRequest.newBuilder()
    .uri(URI.create("https://restlink23telecom.com/api/v1/sms/send"))
    .header("X-API-Key", System.getenv("API_KEY"))
    .header("Content-Type", "application/json")
    .POST(HttpRequest.BodyPublishers.ofString("""
        {
          "to": [
            "+14155551234"
          ],
          "message": "Your verification code is 847291",
          "sender_id": "MyApp"
        }"""))
    .build();

HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println(response.body());

Go

package main

import (
  "fmt"
  "io"
  "net/http"
  "os"
  "strings"
)

func main() {
  payload := strings.NewReader(`{
  "to": [
    "+14155551234"
  ],
  "message": "Your verification code is 847291",
  "sender_id": "MyApp"
}`)

  req, err := http.NewRequest("POST", "https://restlink23telecom.com/api/v1/sms/send", payload)
  if err != nil {
    panic(err)
  }
  req.Header.Set("X-API-Key", os.Getenv("API_KEY"))
  req.Header.Set("Content-Type", "application/json")

  res, err := http.DefaultClient.Do(req)
  if err != nil {
    panic(err)
  }
  defer res.Body.Close()

  data, _ := io.ReadAll(res.Body)
  fmt.Println(string(data))
}

.NET

using System.Text;

using var client = new HttpClient();
client.DefaultRequestHeaders.Add("X-API-Key",
    Environment.GetEnvironmentVariable("API_KEY"));

var json = """
{
  "to": [
    "+14155551234"
  ],
  "message": "Your verification code is 847291",
  "sender_id": "MyApp"
}
""";
var content = new StringContent(json, Encoding.UTF8, "application/json");
var response = await client.PostAsync("https://restlink23telecom.com/api/v1/sms/send", content);

response.EnsureSuccessStatusCode();
Console.WriteLine(await response.Content.ReadAsStringAsync());

Check its status:

cURL

curl https://restlink23telecom.com/api/v1/sms/status/api_42_1743667200123456789_a3f8b2c1d9e45f67 \
  -H "X-API-Key: $API_KEY"

Node.js

const res = await fetch('https://restlink23telecom.com/api/v1/sms/status/api_42_1743667200123456789_a3f8b2c1d9e45f67', {
  method: 'GET',
  headers: { 'X-API-Key': process.env.API_KEY },
});

if (!res.ok) {
  const err = await res.json();
  throw new Error(`${err.error_code}: ${err.description}`);
}
const data = await res.json();
console.log(data);

Python

import os
import requests

res = requests.get(
    "https://restlink23telecom.com/api/v1/sms/status/api_42_1743667200123456789_a3f8b2c1d9e45f67",
    headers={"X-API-Key": os.environ["API_KEY"]},
)
res.raise_for_status()
print(res.json())

PHP

<?php
$ch = curl_init('https://restlink23telecom.com/api/v1/sms/status/api_42_1743667200123456789_a3f8b2c1d9e45f67');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER     => ['X-API-Key: ' . getenv('API_KEY')],
]);

$response = curl_exec($ch);
$status   = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

if ($status !== 200) {
    throw new Exception("HTTP $status: $response");
}
$data = json_decode($response, true);
print_r($data);

Ruby

require "net/http"
require "json"

uri = URI("https://restlink23telecom.com/api/v1/sms/status/api_42_1743667200123456789_a3f8b2c1d9e45f67")
req = Net::HTTP::Get.new(uri)
req["X-API-Key"] = ENV.fetch("API_KEY")

res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |http| http.request(req) }
raise "HTTP #{res.code}: #{res.body}" unless res.is_a?(Net::HTTPSuccess)

puts JSON.parse(res.body)

Java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

HttpClient client = HttpClient.newHttpClient();

HttpRequest request = HttpRequest.newBuilder()
    .uri(URI.create("https://restlink23telecom.com/api/v1/sms/status/api_42_1743667200123456789_a3f8b2c1d9e45f67"))
    .header("X-API-Key", System.getenv("API_KEY"))
    .GET()
    .build();

HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println(response.body());

Go

package main

import (
  "fmt"
  "io"
  "net/http"
  "os"
)

func main() {
  req, err := http.NewRequest("GET", "https://restlink23telecom.com/api/v1/sms/status/api_42_1743667200123456789_a3f8b2c1d9e45f67", nil)
  if err != nil {
    panic(err)
  }
  req.Header.Set("X-API-Key", os.Getenv("API_KEY"))

  res, err := http.DefaultClient.Do(req)
  if err != nil {
    panic(err)
  }
  defer res.Body.Close()

  data, _ := io.ReadAll(res.Body)
  fmt.Println(string(data))
}

.NET

using System.Text;

using var client = new HttpClient();
client.DefaultRequestHeaders.Add("X-API-Key",
    Environment.GetEnvironmentVariable("API_KEY"));

var response = await client.GetAsync("https://restlink23telecom.com/api/v1/sms/status/api_42_1743667200123456789_a3f8b2c1d9e45f67");

response.EnsureSuccessStatusCode();
Console.WriteLine(await response.Content.ReadAsStringAsync());

For webhook receivers in Python, Node.js and PHP, see the delivery webhook examples.

Official SDK packages

Official clients for the three most-requested languages, with automatic 429/5xx retries, stable error_code errors and webhook signature verification built in:

Language	Package	Install
TypeScript / Node 18+	@23telecom/sms	npm install @23telecom/sms
Python 3.9+	telecom23	pip install telecom23
PHP 8.0+	23telecom/sms	composer require 23telecom/sms

TypeScript

import { TelecomClient } from '@23telecom/sms';
const client = new TelecomClient({ apiKey: process.env.API_KEY! });
await client.sms.send({ to: ['+447911123456'], message: 'Hi!', sender_id: 'MyApp' });

Python

from telecom23 import Client
client = Client(api_key=os.environ["API_KEY"])
client.sms.send(to=["+447911123456"], message="Hi!", sender_id="MyApp")

PHP

$client = new \Telecom23\Client(getenv('API_KEY'));
$client->sendSms(['+447911123456'], 'Hi!', 'MyApp');

All three work with sandbox keys (sk_test_…) for free, simulated testing. Ruby, Java, Go and .NET packages are next — until then use the examples above or generate a client from the spec.

AI agents & CLI

There’s also an MCP server and a CLI built on the same API.

Integration tips that save support tickets

• Store the key in API_KEY env var like the examples do — rotating keys then never touches code.
• Treat messages[].message_id as your join key between send responses, status polls and webhook events.
• Handle 429 with backoff (rate limits) and 402 with an alert (balance).
• Make webhook handlers idempotent — retries deliver duplicates by design.