Luxembourg SMS Best Practices, Compliance, and Features

Luxembourg SMS Market Overview

Market Conditions: Luxembourg has a highly developed telecommunications market with near-universal mobile penetration. The country's primary mobile operators include POST Luxembourg, Tango, and Orange Luxembourg. While OTT messaging apps like WhatsApp and Facebook Messenger are popular for personal communications, SMS remains crucial for business communications, particularly for authentication, notifications, and official communications. The market shows a relatively even split between Android and iOS devices, with a slight preference for iOS among business users.

Key SMS Features and Capabilities in Luxembourg

Luxembourg supports standard SMS messaging capabilities with some limitations on advanced features like two-way messaging and concatenation.

Two-way SMS Support

Two-way SMS is not supported in Luxembourg through standard API providers. Businesses requiring interactive messaging solutions should consider alternative communication channels or implement workarounds using separate inbound and outbound numbers.

Concatenated Messages (Segmented SMS)

Support: Concatenated messaging is not supported in Luxembourg through major SMS providers.
Message length rules: Standard SMS length limits apply - 160 characters for GSM-7 encoding, 70 characters for Unicode.
Encoding considerations: Both GSM-7 and UCS-2 encodings are supported, with GSM-7 recommended for optimal character usage and cost efficiency.

MMS Support

MMS messages are automatically converted to SMS with an embedded URL link to view the media content. This ensures compatibility across all carriers while still allowing the delivery of rich media content to end users.

Recipient Phone Number Compatibility

Number Portability

Number portability is not available in Luxembourg for SMS services. This means that messages are routed based on the original carrier assignment of the phone number.

Sending SMS to Landlines

Sending SMS to landline numbers is not supported in Luxembourg. Attempts to send messages to landline numbers will result in a failed delivery and an error response (400 error code 21614) from the SMS API, with no charges applied to the sender's account.

Compliance and Regulatory Guidelines for SMS in Luxembourg

Luxembourg follows strict GDPR and ePrivacy Directive requirements for SMS communications. The National Commission for Data Protection (CNPD) oversees data privacy compliance, while the Institut Luxembourgeois de Régulation (ILR) regulates telecommunications services.

Consent and Opt-In

Explicit Consent Requirements:

• Written or electronic consent must be obtained before sending marketing messages
• Consent must be freely given, specific, informed, and unambiguous
• Documentation of consent must include timestamp, source, and scope
• Existing business relationships may allow for soft opt-in, but must provide immediate opt-out options

Best Practices for Consent:

• Use double opt-in processes for marketing lists
• Maintain detailed consent records including date, time, and method
• Clearly state the types of messages recipients will receive
• Provide transparent information about data usage and sharing

HELP/STOP and Other Commands

• STOP, ARRÊT, and STOPP must be supported (accommodating French, German, and English)
• AIDE and HELP commands must provide support information in relevant languages
• All commands must be case-insensitive
• Response to opt-out commands must be immediate and confirmed

Do Not Call / Do Not Disturb Registries

Luxembourg does not maintain a centralized Do Not Call registry, but businesses must:

• Maintain their own suppression lists
• Honor opt-out requests within 24 hours
• Implement proper list hygiene practices
• Regularly clean contact databases

Time Zone Sensitivity

Luxembourg observes Central European Time (CET/CEST). While no strict time restrictions exist:

• Recommended sending window: 08:00 - 20:00 CET
• Avoid sending on: Sundays and public holidays
• Emergency messages: Can be sent 24/7 if truly urgent
• Best practice: Schedule campaigns between 10:00 - 18:00 on business days

Phone Numbers Options and SMS Sender Types for Luxembourg

Alphanumeric Sender ID

Operator network capability: Supported with dynamic usage
Registration requirements: No pre-registration required
Sender ID preservation: Sender IDs are generally preserved across all major carriers
Length restriction: Maximum 11 characters, alphanumeric only

Long Codes

Domestic vs. International:

• Domestic long codes not supported
• International long codes fully supported

Sender ID preservation: Yes, original sender ID is preserved
Provisioning time: Immediate for international long codes
Use cases:

• Two-factor authentication
• Transactional messages
• Customer support communications

Short Codes

Support: Not currently available in Luxembourg
Alternative: Use international long codes or alphanumeric sender IDs
Use cases: N/A

Restricted SMS Content, Industries, and Use Cases

Restricted Industries:

• Gambling and betting services (unless licensed)
• Adult content and services
• Cryptocurrency promotions
• Unauthorized financial services

Regulated Industries:

• Banking and financial services (require regulatory compliance)
• Healthcare (subject to patient privacy laws)
• Insurance (must follow specific disclosure requirements)

Content Filtering

Known Carrier Filters:

• URLs from unknown shorteners
• Excessive punctuation
• All-capital messages
• Multiple exclamation marks

Best Practices:

• Use official domain URLs
• Maintain consistent sender IDs
• Avoid spam trigger words
• Include clear business identification

Best Practices for Sending SMS in Luxembourg

Messaging Strategy

• Keep messages under 160 characters when possible
• Include clear call-to-action
• Use personalization tokens thoughtfully
• Maintain consistent brand voice

Sending Frequency and Timing

• Limit to 4-5 messages per month per recipient
• Respect business hours and time zones
• Avoid sending during major holidays
• Space out messages appropriately

Localization

• Support French, German, and English
• Consider cultural nuances
• Use appropriate date/time formats
• Respect local holidays and customs

Opt-Out Management

• Process opt-outs within 24 hours
• Maintain centralized suppression lists
• Confirm opt-out with final message
• Regular database cleaning

Testing and Monitoring

• Test across all major carriers
• Monitor delivery rates
• Track engagement metrics
• Regular performance analysis

SMS API integrations for Luxembourg

Twilio

Twilio provides a robust SMS API with comprehensive support for Luxembourg. Integration requires an account SID and auth token for authentication.

import { Twilio } from 'twilio';

// Initialize Twilio client
const client = new Twilio(
  process.env.TWILIO_ACCOUNT_SID,    // Your Account SID
  process.env.TWILIO_AUTH_TOKEN      // Your Auth Token
);

// Function to send SMS to Luxembourg
async function sendSmsToLuxembourg(
  to: string,
  message: string,
  senderId: string
): Promise<void> {
  try {
    // Ensure number is in E.164 format for Luxembourg
    const formattedNumber = to.startsWith('+352') ? to : `+352${to}`;
    
    const response = await client.messages.create({
      body: message,
      from: senderId,    // Alphanumeric sender ID or long code
      to: formattedNumber,
      // Optional parameters for delivery tracking
      statusCallback: 'https://your-webhook.com/status'
    });
    
    console.log(`Message sent successfully! SID: ${response.sid}`);
  } catch (error) {
    console.error('Error sending message:', error);
    throw error;
  }
}

Sinch

Sinch offers a straightforward REST API for sending SMS to Luxembourg, with support for both JSON and XML formats.

import axios from 'axios';

interface SinchSmsConfig {
  apiToken: string;
  servicePlanId: string;
  senderId: string;
}

class SinchSmsService {
  private readonly baseUrl = 'https://sms.api.sinch.com/xms/v1';
  private readonly config: SinchSmsConfig;

  constructor(config: SinchSmsConfig) {
    this.config = config;
  }

  async sendSms(to: string, message: string): Promise<void> {
    try {
      const response = await axios.post(
        `${this.baseUrl}/${this.config.servicePlanId}/batches`,
        {
          from: this.config.senderId,
          to: [to],
          body: message
        },
        {
          headers: {
            'Authorization': `Bearer ${this.config.apiToken}`,
            'Content-Type': 'application/json'
          }
        }
      );
      
      console.log('Message sent:', response.data.id);
    } catch (error) {
      console.error('Sinch SMS error:', error);
      throw error;
    }
  }
}

MessageBird

MessageBird provides a feature-rich API with strong support for European markets including Luxembourg.

import messagebird from 'messagebird';

class MessageBirdService {
  private client: any;

  constructor(apiKey: string) {
    this.client = messagebird(apiKey);
  }

  sendSms(
    to: string,
    message: string,
    senderId: string
  ): Promise<any> {
    return new Promise((resolve, reject) => {
      this.client.messages.create({
        originator: senderId,
        recipients: [to],
        body: message,
        // Optional parameters
        reportUrl: 'https://your-webhook.com/delivery-reports'
      }, (err: any, response: any) => {
        if (err) {
          reject(err);
        } else {
          resolve(response);
        }
      });
    });
  }
}

Plivo

Plivo offers reliable SMS delivery to Luxembourg with detailed delivery reporting.

import plivo from 'plivo';

class PlivoSmsService {
  private client: any;

  constructor(authId: string, authToken: string) {
    this.client = new plivo.Client(authId, authToken);
  }

  async sendSms(
    to: string,
    message: string,
    senderId: string
  ): Promise<void> {
    try {
      const response = await this.client.messages.create({
        src: senderId,
        dst: to,
        text: message,
        // Optional parameters
        url: 'https://your-webhook.com/delivery-status',
        method: 'POST'
      });
      
      console.log('Message sent:', response.messageUuid[0]);
    } catch (error) {
      console.error('Plivo error:', error);
      throw error;
    }
  }
}

API Rate Limits and Throughput

• Default rate limits vary by provider (typically 1-10 messages per second)
• Implement exponential backoff for retry logic
• Use batch APIs for high-volume sending
• Consider queue implementation for large campaigns:

import Queue from 'bull';

const smsQueue = new Queue('sms-queue', {
  redis: process.env.REDIS_URL
});

// Add rate limiting
smsQueue.process(10, async (job) => {
  // Process SMS sending logic here
});

Error Handling and Reporting

• Implement comprehensive logging
• Monitor delivery receipts
• Track common error codes:
  • 4xx: Client errors (invalid numbers, formatting)
  • 5xx: Server errors (retry recommended)

Recap and Additional Resources

Key Takeaways:

• Always format numbers in E.164 format (+352)
• Implement proper error handling and retry logic
• Monitor delivery rates and engagement
• Maintain compliance with GDPR and local regulations

Next Steps:

1. Review the ILR Telecommunications Guidelines
2. Consult with legal counsel for compliance review
3. Set up monitoring and reporting systems
4. Test thoroughly across all major carriers

Additional Resources:

• Luxembourg Data Protection Authority (CNPD)
• European Electronic Communications Code
• SMS Best Practices Guide