From a verification code to an order update. Your system sends it. Your customer gets the message.

# Run on your server; load secrets from your environment.
curl --get 'https://togethersms.com/sendsms.php' \
  --connect-timeout 10 --max-time 20 \
  --data-urlencode "user=${TOGETHER_SMS_USER}" \
  --data-urlencode "password=${TOGETHER_SMS_PASSWORD}" \
  --data-urlencode 'action=get'

# Sending is a separate request. Use an approved test recipient.
# Add numbers, sender, message and lang; omit action=get.

// Backend only. Never expose provider credentials in a browser.
const query = new URLSearchParams({
  user: process.env.TOGETHER_SMS_USER,
  password: process.env.TOGETHER_SMS_PASSWORD,
  action: 'get'
});
const response = await fetch(
  'https://togethersms.com/sendsms.php?' + query,
  { redirect: 'error', signal: AbortSignal.timeout(20000) }
);
const body = (await response.text()).trim();
if (!response.ok || !/^[0-9]+(?:\.[0-9]+)?$/.test(body)) {
  throw new Error('Balance request was not accepted');
}
// Keep decimal precision; do not log the request URL.

<?php
// Backend only. Secrets come from your deployment environment.
$query = http_build_query(array(
  'user' => getenv('TOGETHER_SMS_USER'),
  'password' => getenv('TOGETHER_SMS_PASSWORD'),
  'action' => 'get'
), '', '&', PHP_QUERY_RFC3986);
$ch = curl_init('https://togethersms.com/sendsms.php?' . $query);
curl_setopt_array($ch, array(
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_FOLLOWLOCATION => false,
  CURLOPT_CONNECTTIMEOUT => 10,
  CURLOPT_TIMEOUT => 20
));
$body = curl_exec($ch);
$status = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
if ($body === false || $status < 200 || $status >= 300 ||
    !preg_match('/\A[0-9]+(?:\.[0-9]+)?\z/', trim($body))) {
  throw new RuntimeException('Balance request was not accepted');
}

# Backend only. Requires the requests package.
import os
import re
import requests

response = requests.get(
    'https://togethersms.com/sendsms.php',
    params={
        'user': os.environ['TOGETHER_SMS_USER'],
        'password': os.environ['TOGETHER_SMS_PASSWORD'],
        'action': 'get'
    },
    timeout=(10, 20),
    allow_redirects=False
)
body = response.text.strip()
if not (200 <= response.status_code < 300 and
        re.fullmatch(r'[0-9]+(?:\.[0-9]+)?', body)):
    raise RuntimeError('Balance request was not accepted')
# Timeout values are connect/read timeouts, not a strict total deadline.

// Backend only. Use a supported .NET runtime.
using var handler = new HttpClientHandler { AllowAutoRedirect = false };
using var client = new HttpClient(handler) {
    Timeout = TimeSpan.FromSeconds(20)
};
string user = Environment.GetEnvironmentVariable("TOGETHER_SMS_USER")!;
string password = Environment.GetEnvironmentVariable("TOGETHER_SMS_PASSWORD")!;
string url = "https://togethersms.com/sendsms.php?user=" +
    Uri.EscapeDataString(user) + "&password=" +
    Uri.EscapeDataString(password) + "&action=get";
using var response = await client.GetAsync(url);
string body = (await response.Content.ReadAsStringAsync()).Trim();
if (!response.IsSuccessStatusCode ||
    !System.Text.RegularExpressions.Regex.IsMatch(
        body, @"\A[0-9]+(?:\.[0-9]+)?\z")) {
    throw new InvalidOperationException("Balance request was not accepted");
}